diff --git a/python/PyQt6/core/__init__.py.in b/python/PyQt6/core/__init__.py.in
index b57fc3eea27c..f8a6aa9474f4 100644
--- a/python/PyQt6/core/__init__.py.in
+++ b/python/PyQt6/core/__init__.py.in
@@ -70,9 +70,9 @@ def _date_range_repr(self):
 QgsDateTimeRange.__repr__ = _datetime_range_repr
 QgsDateRange.__repr__ = _date_range_repr
 
-
 QgsProperty.__bool__ = lambda self: self.propertyType() != Qgis.PropertyType.Invalid
 QgsOptionalExpression.__bool__ = lambda self: self.enabled()
+QgsUnsetAttributeValue.__hash__ = lambda self: 2178310
 
 # add some __repr__ methods to processing classes
 def _processing_source_repr(self):
diff --git a/python/core/__init__.py.in b/python/core/__init__.py.in
index 3a2be42fff18..50d4f624393a 100644
--- a/python/core/__init__.py.in
+++ b/python/core/__init__.py.in
@@ -73,7 +73,7 @@ QgsDateRange.__repr__ = _date_range_repr
 
 QgsProperty.__bool__ = lambda self: self.propertyType() != Qgis.PropertyType.Invalid
 QgsOptionalExpression.__bool__ = lambda self: self.enabled()
-
+QgsUnsetAttributeValue.__hash__ = lambda self: 2178310
 
 # add some __repr__ methods to processing classes
 def _processing_source_repr(self):
diff --git a/src/core/providers/memory/qgsmemoryprovider.cpp b/src/core/providers/memory/qgsmemoryprovider.cpp
index d9cff37c84b1..f4814ffee70a 100644
--- a/src/core/providers/memory/qgsmemoryprovider.cpp
+++ b/src/core/providers/memory/qgsmemoryprovider.cpp
@@ -682,6 +682,9 @@ bool QgsMemoryProvider::changeAttributeValues( const QgsChangedAttributesMap &at
         continue;
 
       QVariant attrValue = it2.value();
+      if ( attrValue.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+        continue;
+
       // Check attribute conversion
       const bool conversionError { ! QgsVariantUtils::isNull( attrValue )
                                    && ! mFields.at( it2.key() ).convertCompatible( attrValue, &errorMessage ) };
diff --git a/src/core/providers/ogr/qgsogrprovider.cpp b/src/core/providers/ogr/qgsogrprovider.cpp
index 5cbbfe351fed..bef28b60b4b8 100644
--- a/src/core/providers/ogr/qgsogrprovider.cpp
+++ b/src/core/providers/ogr/qgsogrprovider.cpp
@@ -2763,7 +2763,7 @@ bool QgsOgrProvider::changeAttributeValues( const QgsChangedAttributesMap &attr_
     {
       useUpdate = false;
     }
-    if ( useUpdate )
+    if ( useUpdate && val.userType() != qMetaTypeId<QgsUnsetAttributeValue >() )
     {
       QString sql = QStringLiteral( "UPDATE %1 SET %2 = %3" )
                     .arg( QString::fromUtf8( QgsOgrProviderUtils::quotedIdentifier( mOgrLayer->name(), mGDALDriverName ) ) )
@@ -2838,6 +2838,9 @@ bool QgsOgrProvider::changeAttributeValues( const QgsChangedAttributesMap &attr_
     for ( QgsAttributeMap::const_iterator it2 = attr.begin(); it2 != attr.end(); ++it2 )
     {
       int f = it2.key();
+      if ( it2->userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+        continue;
+
       if ( mFirstFieldIsFid )
       {
         if ( f == 0 )
diff --git a/src/core/qgsfield.cpp b/src/core/qgsfield.cpp
index 056bd9b4afc3..1a64d9565070 100644
--- a/src/core/qgsfield.cpp
+++ b/src/core/qgsfield.cpp
@@ -20,6 +20,7 @@
 #include "qgsapplication.h"
 #include "qgsreferencedgeometry.h"
 #include "qgsvariantutils.h"
+#include "qgsunsetattributevalue.h"
 
 #include <QDataStream>
 #include <QIcon>
@@ -482,6 +483,11 @@ bool QgsField::convertCompatible( QVariant &v, QString *errorMessage ) const
     return true;
   }
 
+  if ( v.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+  {
+    return true;
+  }
+
   if ( d->type == QMetaType::Type::Int && v.toInt() != v.toLongLong() )
   {
     v = QgsVariantUtils::createNullVariant( d->type );
diff --git a/src/providers/hana/qgshanaprovider.cpp b/src/providers/hana/qgshanaprovider.cpp
index aab0cc94c574..ad1bb335aa5b 100644
--- a/src/providers/hana/qgshanaprovider.cpp
+++ b/src/providers/hana/qgshanaprovider.cpp
@@ -748,6 +748,11 @@ bool QgsHanaProvider::addFeatures( QgsFeatureList &flist, Flags flags )
         const int fieldIndex = fieldIds[i];
         const AttributeField &field = mAttributeFields.at( fieldIndex );
         QVariant attrValue = fieldIndex < attrs.length() ? attrs.at( fieldIndex ) : QgsVariantUtils::createNullVariant( QMetaType::Type::LongLong );
+
+        // no default value clause handling supported in this provider, best we can do for now is set to NULL
+        if ( attrValue.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+          attrValue = QVariant();
+
         if ( pkFields[i] )
         {
           hasIdValue = hasIdValue || !attrValue.isNull();
@@ -1175,6 +1180,9 @@ bool QgsHanaProvider::changeAttributeValues( const QgsChangedAttributesMap &attr
         if ( field.name.isEmpty() || field.isAutoIncrement )
           continue;
 
+        if ( it2->userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+          continue;
+
         pkChanged = pkChanged || mPrimaryKeyAttrs.contains( fieldIndex );
         auto qType = mFields.at( fieldIndex ).type();
         if ( field.type == QgsHanaDataType::Geometry && qType == QMetaType::Type::QString )
@@ -1202,7 +1210,11 @@ bool QgsHanaProvider::changeAttributeValues( const QgsChangedAttributesMap &attr
         if ( field.name.isEmpty() || field.isAutoIncrement )
           continue;
 
-        setStatementValue( stmtUpdate, paramIndex, field, *attrIt );
+        const QVariant attrValue = *attrIt;
+        if ( attrValue.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+          continue;
+
+        setStatementValue( stmtUpdate, paramIndex, field, attrValue );
         ++paramIndex;
       }
 
diff --git a/src/providers/mssql/qgsmssqlprovider.cpp b/src/providers/mssql/qgsmssqlprovider.cpp
index 5396c7bec5a2..19f0417dc646 100644
--- a/src/providers/mssql/qgsmssqlprovider.cpp
+++ b/src/providers/mssql/qgsmssqlprovider.cpp
@@ -1202,6 +1202,9 @@ bool QgsMssqlProvider::addFeatures( QgsFeatureList &flist, Flags flags )
       if ( fld.name().isEmpty() )
         continue; // invalid
 
+      if ( attrs.at( i ).userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+        continue;
+
       if ( mDefaultValues.contains( i ) && mDefaultValues.value( i ) == attrs.at( i ).toString() )
         continue; // skip fields having default values
 
@@ -1300,6 +1303,9 @@ bool QgsMssqlProvider::addFeatures( QgsFeatureList &flist, Flags flags )
       if ( fld.name().isEmpty() )
         continue; // invalid
 
+      if ( attrs.at( i ).userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+        continue;
+
       if ( mDefaultValues.contains( i ) && mDefaultValues.value( i ) == attrs.at( i ).toString() )
         continue; // skip fields having default values
 
@@ -1554,6 +1560,9 @@ bool QgsMssqlProvider::changeAttributeValues( const QgsChangedAttributesMap &att
       if ( fld.name().isEmpty() )
         continue; // invalid
 
+      if ( it2.value().userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+        continue;
+
       if ( mComputedColumns.contains( fld.name() ) )
         continue; // skip computed columns because they are done server side.
 
@@ -1593,6 +1602,9 @@ bool QgsMssqlProvider::changeAttributeValues( const QgsChangedAttributesMap &att
       if ( fld.name().isEmpty() )
         continue; // invalid
 
+      if ( it2.value().userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+        continue;
+
       if ( mComputedColumns.contains( fld.name() ) )
         continue; // skip computed columns because they are done server side.
 
diff --git a/src/providers/oracle/qgsoracleprovider.cpp b/src/providers/oracle/qgsoracleprovider.cpp
index f154bbfc8f00..5fc066723dd1 100644
--- a/src/providers/oracle/qgsoracleprovider.cpp
+++ b/src/providers/oracle/qgsoracleprovider.cpp
@@ -1394,7 +1394,9 @@ bool QgsOracleProvider::addFeatures( QgsFeatureList &flist, QgsFeatureSink::Flag
         QVariant value = attributevec.value( fieldId[i], QVariant() );
 
         QgsField fld = field( fieldId[i] );
-        if ( ( QgsVariantUtils::isNull( value ) && mPrimaryKeyAttrs.contains( i ) && !defaultValues.at( i ).isEmpty() ) || ( value.toString() == defaultValues[i] ) )
+        if ( ( QgsVariantUtils::isNull( value ) && mPrimaryKeyAttrs.contains( i ) && !defaultValues.at( i ).isEmpty() )
+             || ( value.toString() == defaultValues[i] )
+             || value.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
         {
           value = evaluateDefaultExpression( defaultValues[i], fld.type() );
         }
@@ -1860,6 +1862,10 @@ bool QgsOracleProvider::changeAttributeValues( const QgsChangedAttributesMap &at
             QgsLogger::warning( tr( "Changing the value of GENERATED field %1 is not allowed." ).arg( fld.name() ) );
             continue;
           }
+          if ( siter.value().userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+          {
+            continue;
+          }
 
           pkChanged = pkChanged || mPrimaryKeyAttrs.contains( siter.key() );
 
diff --git a/src/providers/postgres/qgspostgresprovider.cpp b/src/providers/postgres/qgspostgresprovider.cpp
index 9971e91cba45..189972c4f02c 100644
--- a/src/providers/postgres/qgspostgresprovider.cpp
+++ b/src/providers/postgres/qgspostgresprovider.cpp
@@ -2287,7 +2287,7 @@ bool QgsPostgresProvider::addFeatures( QgsFeatureList &flist, Flags flags )
           QVariant v2 = attrs2.value( idx, QgsVariantUtils::createNullVariant( QMetaType::Type::Int ) );
           // a PK field with a sequence val is auto populate by QGIS with this default
           // we are only interested in non default values
-          if ( !QgsVariantUtils::isNull( v2 ) && v2.toString() != defaultValue )
+          if ( !QgsVariantUtils::isNull( v2 ) && v2.toString() != defaultValue && v2.userType() != qMetaTypeId< QgsUnsetAttributeValue >() )
           {
             foundNonEmptyPK = true;
             break;
@@ -2298,7 +2298,7 @@ bool QgsPostgresProvider::addFeatures( QgsFeatureList &flist, Flags flags )
 
       if ( !skipSinglePKField )
       {
-        for ( int idx : mPrimaryKeyAttrs )
+        for ( int idx : std::as_const( mPrimaryKeyAttrs ) )
         {
           if ( mIdentityFields[idx] == 'a' )
             overrideIdentity = true;
@@ -2327,7 +2327,6 @@ bool QgsPostgresProvider::addFeatures( QgsFeatureList &flist, Flags flags )
         continue;
 
       QString fieldname = mAttributeFields.at( idx ).name();
-
       if ( !mGeneratedValues.value( idx, QString() ).isEmpty() )
       {
         QgsDebugMsgLevel( QStringLiteral( "Skipping field %1 (idx %2) which is GENERATED." ).arg( fieldname, QString::number( idx ) ), 2 );
@@ -2469,7 +2468,7 @@ bool QgsPostgresProvider::addFeatures( QgsFeatureList &flist, Flags flags )
         QVariant value = attrIdx < attrs.length() ? attrs.at( attrIdx ) : QgsVariantUtils::createNullVariant( QMetaType::Type::Int );
 
         QString v;
-        if ( QgsVariantUtils::isNull( value ) )
+        if ( QgsVariantUtils::isNull( value ) || value.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
         {
           QgsField fld = field( attrIdx );
           v = paramValue( defaultValues[i], defaultValues[i] );
@@ -2949,6 +2948,10 @@ bool QgsPostgresProvider::changeAttributeValues( const QgsChangedAttributesMap &
       {
         try
         {
+          const QVariant attributeValue = siter.value();
+          if ( attributeValue.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+            continue;
+
           QgsField fld = field( siter.key() );
 
           pkChanged = pkChanged || mPrimaryKeyAttrs.contains( siter.key() );
@@ -2965,13 +2968,13 @@ bool QgsPostgresProvider::changeAttributeValues( const QgsChangedAttributesMap &
           delim = ',';
 
           QString defVal = defaultValueClause( siter.key() );
-          if ( qgsVariantEqual( *siter, defVal ) )
+          if ( qgsVariantEqual( attributeValue, defVal ) )
           {
             sql += defVal.isNull() ? "NULL" : defVal;
           }
           else if ( fld.typeName() == QLatin1String( "geometry" ) )
           {
-            QString val = geomAttrToString( siter.value(), connectionRO() );
+            QString val = geomAttrToString( attributeValue, connectionRO() );
 
             sql += QStringLiteral( "%1(%2)" )
                      .arg( connectionRO()->majorVersion() < 2 ? "geomfromewkt" : "st_geomfromewkt", quotedValue( val ) );
@@ -2979,25 +2982,25 @@ bool QgsPostgresProvider::changeAttributeValues( const QgsChangedAttributesMap &
           else if ( fld.typeName() == QLatin1String( "geography" ) )
           {
             sql += QStringLiteral( "st_geographyfromtext(%1)" )
-                     .arg( quotedValue( siter->toString() ) );
+                     .arg( quotedValue( attributeValue.toString() ) );
           }
           else if ( fld.typeName() == QLatin1String( "jsonb" ) )
           {
             sql += QStringLiteral( "%1::jsonb" )
-                     .arg( quotedJsonValue( siter.value() ) );
+                     .arg( quotedJsonValue( attributeValue ) );
           }
           else if ( fld.typeName() == QLatin1String( "json" ) )
           {
             sql += QStringLiteral( "%1::json" )
-                     .arg( quotedJsonValue( siter.value() ) );
+                     .arg( quotedJsonValue( attributeValue ) );
           }
           else if ( fld.typeName() == QLatin1String( "bytea" ) )
           {
-            sql += quotedByteaValue( siter.value() );
+            sql += quotedByteaValue( attributeValue );
           }
           else
           {
-            sql += quotedValue( *siter );
+            sql += quotedValue( attributeValue );
           }
         }
         catch ( PGFieldNotFound )
@@ -3328,6 +3331,12 @@ bool QgsPostgresProvider::changeFeatures( const QgsChangedAttributesMap &attr_ma
             continue;
           }
 
+          const QVariant value = siter.value();
+          if ( value.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+          {
+            continue;
+          }
+
           numChangedFields++;
 
           sql += delim + QStringLiteral( "%1=" ).arg( quotedIdentifier( fld.name() ) );
@@ -3335,32 +3344,32 @@ bool QgsPostgresProvider::changeFeatures( const QgsChangedAttributesMap &attr_ma
 
           if ( fld.typeName() == QLatin1String( "geometry" ) )
           {
-            QString val = geomAttrToString( siter.value(), connectionRO() );
+            QString val = geomAttrToString( value, connectionRO() );
             sql += QStringLiteral( "%1(%2)" )
                      .arg( connectionRO()->majorVersion() < 2 ? "geomfromewkt" : "st_geomfromewkt", quotedValue( val ) );
           }
           else if ( fld.typeName() == QLatin1String( "geography" ) )
           {
             sql += QStringLiteral( "st_geographyfromtext(%1)" )
-                     .arg( quotedValue( siter->toString() ) );
+                     .arg( quotedValue( value.toString() ) );
           }
           else if ( fld.typeName() == QLatin1String( "jsonb" ) )
           {
             sql += QStringLiteral( "%1::jsonb" )
-                     .arg( quotedJsonValue( siter.value() ) );
+                     .arg( quotedJsonValue( value ) );
           }
           else if ( fld.typeName() == QLatin1String( "json" ) )
           {
             sql += QStringLiteral( "%1::json" )
-                     .arg( quotedJsonValue( siter.value() ) );
+                     .arg( quotedJsonValue( value ) );
           }
           else if ( fld.typeName() == QLatin1String( "bytea" ) )
           {
-            sql += quotedByteaValue( siter.value() );
+            sql += quotedByteaValue( value );
           }
           else
           {
-            sql += quotedValue( *siter );
+            sql += quotedValue( value );
           }
         }
         catch ( PGFieldNotFound )
diff --git a/src/providers/spatialite/qgsspatialiteprovider.cpp b/src/providers/spatialite/qgsspatialiteprovider.cpp
index acd60202ab40..9189a73d9781 100644
--- a/src/providers/spatialite/qgsspatialiteprovider.cpp
+++ b/src/providers/spatialite/qgsspatialiteprovider.cpp
@@ -4131,7 +4131,10 @@ bool QgsSpatiaLiteProvider::addFeatures( QgsFeatureList &flist, Flags flags )
 
       for ( int i = 0; i < attributevec.count(); ++i )
       {
-        if ( mDefaultValues.contains( i ) && ( mDefaultValues.value( i ) == attributevec.at( i ).toString() || !attributevec.at( i ).isValid() ) )
+        if (
+          ( mDefaultValues.contains( i ) && ( mDefaultValues.value( i ) == attributevec.at( i ).toString() || !attributevec.at( i ).isValid() ) )
+          || ( attributevec.at( i ).userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+        )
         {
           defaultIndexes.push_back( i );
           continue;
@@ -4597,6 +4600,8 @@ bool QgsSpatiaLiteProvider::changeAttributeValues( const QgsChangedAttributesMap
       {
         QgsField fld = field( siter.key() );
         const QVariant &val = siter.value();
+        if ( val.userType() == qMetaTypeId< QgsUnsetAttributeValue >() )
+          continue;
 
         if ( !first )
           sql += ',';
diff --git a/tests/src/core/testqgsfield.cpp b/tests/src/core/testqgsfield.cpp
index b88ac69bb074..d9c703305a7c 100644
--- a/tests/src/core/testqgsfield.cpp
+++ b/tests/src/core/testqgsfield.cpp
@@ -26,6 +26,7 @@
 #include "qgsapplication.h"
 #include "qgstest.h"
 #include "qgsreferencedgeometry.h"
+#include "qgsunsetattributevalue.h"
 
 class TestQgsField : public QObject
 {
@@ -603,6 +604,9 @@ void TestQgsField::convertCompatible()
   QVERIFY( stringField.convertCompatible( nullDouble ) );
   QCOMPARE( static_cast<QMetaType::Type>( nullDouble.userType() ), QMetaType::Type::QString );
   QVERIFY( nullDouble.isNull() );
+  QVariant unsetValue = QgsUnsetAttributeValue( QStringLiteral( "Autonumber" ) );
+  QVERIFY( stringField.convertCompatible( unsetValue ) );
+  QCOMPARE( static_cast<QMetaType::Type>( unsetValue.userType() ), qMetaTypeId< QgsUnsetAttributeValue >() );
 
   //test double
   const QgsField doubleField( QStringLiteral( "double" ), QMetaType::Type::Double, QStringLiteral( "double" ) );
@@ -636,6 +640,9 @@ void TestQgsField::convertCompatible()
   QVERIFY( doubleField.convertCompatible( nullDouble ) );
   QCOMPARE( static_cast<QMetaType::Type>( nullDouble.userType() ), QMetaType::Type::Double );
   QVERIFY( nullDouble.isNull() );
+  unsetValue = QgsUnsetAttributeValue( QStringLiteral( "Autonumber" ) );
+  QVERIFY( doubleField.convertCompatible( unsetValue ) );
+  QCOMPARE( static_cast<QMetaType::Type>( unsetValue.userType() ), qMetaTypeId< QgsUnsetAttributeValue >() );
 
   //test special rules
 
diff --git a/tests/src/python/provider_python.py b/tests/src/python/provider_python.py
index ad6ab99e0f2a..c0a8dfb0cbb4 100644
--- a/tests/src/python/provider_python.py
+++ b/tests/src/python/provider_python.py
@@ -14,6 +14,7 @@
 __copyright__ = "Copyright 2018, The QGIS Project"
 
 from qgis.PyQt.QtCore import QVariant
+from qgis._core import QgsUnsetAttributeValue
 from qgis.core import (
     Qgis,
     QgsAbstractFeatureIterator,
@@ -34,6 +35,7 @@
     QgsSpatialIndex,
     QgsVectorDataProvider,
     QgsVectorLayer,
+    QgsUnsetAttributeValue,
 )
 
 
@@ -421,6 +423,8 @@ def changeAttributeValues(self, attr_map):
             except KeyError:
                 continue
             for k, v in attrs.items():
+                if isinstance(v, QgsUnsetAttributeValue):
+                    continue
                 f.setAttribute(k, v)
         self.clearMinMaxCache()
         return True
diff --git a/tests/src/python/providertestbase.py b/tests/src/python/providertestbase.py
index 6355499210a0..bf154164af67 100644
--- a/tests/src/python/providertestbase.py
+++ b/tests/src/python/providertestbase.py
@@ -31,6 +31,7 @@
     QgsVectorDataProvider,
     QgsVectorLayerFeatureSource,
     QgsVectorLayerUtils,
+    QgsUnsetAttributeValue,
 )
 
 from featuresourcetestbase import FeatureSourceTestCase
@@ -1003,6 +1004,86 @@ def testAddFeatureFastInsert(self):
             )
             self.assertEqual(l.dataProvider().featureCount(), 7)
 
+    def testAddFeatureUnsetAttributes(self):
+        if not getattr(self, "getEditableLayer", None):
+            return
+
+        l = self.getEditableLayer()
+        self.assertTrue(l.isValid())
+
+        f1 = QgsFeature()
+        f1.setAttributes(
+            [
+                6,
+                -220,
+                QgsUnsetAttributeValue(),
+                "String",
+                "15",
+                NULL,
+                NULL,
+                NULL,
+            ]
+        )
+        f1.setGeometry(QgsGeometry.fromWkt("Point (-72.345 71.987)"))
+
+        f2 = QgsFeature()
+        f2.setAttributes(
+            [
+                7,
+                QgsUnsetAttributeValue(),
+                "Coconut",
+                "CoCoNut",
+                "13",
+                NULL,
+                NULL,
+                NULL,
+            ]
+        )
+
+        if (
+            l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.AddFeatures
+        ):
+            # expect success
+            result, added = l.dataProvider().addFeatures(
+                [f1, f2], QgsFeatureSink.Flag.FastInsert
+            )
+            self.assertTrue(
+                result,
+                "Provider reported AddFeatures capability, but returned False to addFeatures using QgsUnsetAttributeValues",
+            )
+            self.assertEqual(l.dataProvider().featureCount(), 7)
+
+            features = [f for f in l.dataProvider().getFeatures()]
+            self.assertEqual(len(features), 7)
+            f6 = [f for f in features if f[0] == 6][0]
+            f7 = [f for f in features if f[0] == 7][0]
+            self.assertEqual(f6[1], -220)
+            self.assertTrue(
+                isinstance(f6[2], QgsUnsetAttributeValue)
+                or f6[2] == NULL
+                or str(f6[2]) == "",
+                f"Expected null/unset value, got {f6[2]}",
+            )
+            self.assertEqual(f6[3], "String")
+            self.assertEqual(f6[4], "15")
+            self.assertEqual(f6[5], NULL)
+            self.assertEqual(f6[6], NULL)
+            self.assertEqual(f6[7], NULL)
+
+            self.assertTrue(
+                isinstance(f7[1], QgsUnsetAttributeValue)
+                or f7[1] == NULL
+                or str(f7[1]) == "",
+                f"Expected null/unset value, got {f7[1]}",
+            )
+            self.assertEqual(f7[2], "Coconut")
+            self.assertEqual(f7[3], "CoCoNut")
+            self.assertEqual(f7[4], "13")
+            self.assertEqual(f7[5], NULL)
+            self.assertEqual(f7[6], NULL)
+            self.assertEqual(f7[7], NULL)
+
     def testAddFeatureMissingAttributes(self):
         if not getattr(self, "getEditableLayer", None):
             return
@@ -1386,6 +1467,80 @@ def testChangeAttributes(self):
                 "Provider reported no ChangeAttributeValues capability, but returned true to changeAttributeValues",
             )
 
+    def testChangeAttributesUnsetValue(self):
+        if not getattr(self, "getEditableLayer", None):
+            return
+
+        l = self.getEditableLayer()
+        self.assertTrue(l.isValid())
+
+        # find 2 features to change
+        features = [f for f in l.dataProvider().getFeatures()]
+        # need to keep order here
+        to_change = [f for f in features if f.attributes()[0] == 1]
+        to_change.extend([f for f in features if f.attributes()[0] == 3])
+        # changes by feature id, for changeAttributeValues call
+        changes = {
+            to_change[0].id(): {1: QgsUnsetAttributeValue(), 3: "new string"},
+            to_change[1].id(): {1: 502, 4: QgsUnsetAttributeValue()},
+        }
+        # changes by pk, for testing after retrieving changed features
+        new_attr_map = {1: {3: "new string"}, 3: {1: 502}}
+
+        if (
+            l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.ChangeAttributeValues
+        ):
+            # expect success
+            result = l.dataProvider().changeAttributeValues(changes)
+            self.assertTrue(
+                result,
+                "Provider reported ChangeAttributeValues capability, but returned False to changeAttributeValues",
+            )
+
+            # check result
+            self.testGetFeatures(l.dataProvider(), changed_attributes=new_attr_map)
+
+        else:
+            # expect fail
+            self.assertFalse(
+                l.dataProvider().changeAttributeValues(changes),
+                "Provider reported no ChangeAttributeValues capability, but returned true to changeAttributeValues",
+            )
+
+    def testChangeAttributesOnlyUnsetValue(self):
+        if not getattr(self, "getEditableLayer", None):
+            return
+
+        l = self.getEditableLayer()
+        self.assertTrue(l.isValid())
+
+        # find 2 features to change
+        features = [f for f in l.dataProvider().getFeatures()]
+        # need to keep order here
+        to_change = [f for f in features if f.attributes()[0] == 1]
+        to_change.extend([f for f in features if f.attributes()[0] == 3])
+        # changes by feature id, for changeAttributeValues call
+        changes = {
+            to_change[0].id(): {1: QgsUnsetAttributeValue()},
+            to_change[1].id(): {4: QgsUnsetAttributeValue()},
+        }
+        if (
+            l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.ChangeAttributeValues
+        ):
+            l.dataProvider().changeAttributeValues(changes)
+
+            # check result
+            self.testGetFeatures(l.dataProvider())
+
+        else:
+            # expect fail
+            self.assertFalse(
+                l.dataProvider().changeAttributeValues(changes),
+                "Provider reported no ChangeAttributeValues capability, but returned true to changeAttributeValues",
+            )
+
     def testChangeAttributesConstraintViolation(self):
         """Checks that changing attributes violating a DB-level CHECK constraint returns false
         the provider test case must provide an editable layer with a text field
@@ -1591,6 +1746,83 @@ def testChangeFeatures(self):
                 "Provider reported no ChangeAttributeValues capability, but returned true to changeFeatures",
             )
 
+    def testChangeFeaturesUnsetAttribute(self):
+        if not getattr(self, "getEditableLayer", None):
+            return
+
+        l = self.getEditableLayer()
+        self.assertTrue(l.isValid())
+
+        features = [f for f in l.dataProvider().getFeatures()]
+
+        # find 2 features to change attributes for
+        features = [f for f in l.dataProvider().getFeatures()]
+        # need to keep order here
+        to_change = [f for f in features if f.attributes()[0] == 1]
+        to_change.extend([f for f in features if f.attributes()[0] == 2])
+        # changes by feature id, for changeAttributeValues call
+        attribute_changes = {
+            to_change[0].id(): {1: QgsUnsetAttributeValue(), 3: "new string"},
+            to_change[1].id(): {1: 502, 4: QgsUnsetAttributeValue()},
+        }
+        # changes by pk, for testing after retrieving changed features
+        new_attr_map = {1: {3: "new string"}, 2: {1: 502}}
+
+        # find 2 features to change geometries for
+        to_change = [f for f in features if f.attributes()[0] == 1]
+        to_change.extend([f for f in features if f.attributes()[0] == 3])
+        # changes by feature id, for changeGeometryValues call
+        geometry_changes = {
+            to_change[0].id(): QgsGeometry.fromWkt("Point (10 20)"),
+            to_change[1].id(): QgsGeometry(),
+        }
+        # changes by pk, for testing after retrieving changed features
+        new_geom_map = {1: QgsGeometry.fromWkt("Point ( 10 20 )"), 3: QgsGeometry()}
+
+        if (
+            l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.ChangeGeometries
+            and l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.ChangeAttributeValues
+        ):
+            # expect success
+            result = l.dataProvider().changeFeatures(
+                attribute_changes, geometry_changes
+            )
+            self.assertTrue(
+                result,
+                "Provider reported ChangeGeometries and ChangeAttributeValues capability, but returned False to changeFeatures",
+            )
+
+            # check result
+            self.testGetFeatures(
+                l.dataProvider(),
+                changed_attributes=new_attr_map,
+                changed_geometries=new_geom_map,
+            )
+
+            # change empty list, should return true for consistency
+            self.assertTrue(l.dataProvider().changeFeatures({}, {}))
+
+        elif (
+            not l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.ChangeGeometries
+        ):
+            # expect fail
+            self.assertFalse(
+                l.dataProvider().changeFeatures(attribute_changes, geometry_changes),
+                "Provider reported no ChangeGeometries capability, but returned true to changeFeatures",
+            )
+        elif (
+            not l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.ChangeAttributeValues
+        ):
+            # expect fail
+            self.assertFalse(
+                l.dataProvider().changeFeatures(attribute_changes, geometry_changes),
+                "Provider reported no ChangeAttributeValues capability, but returned true to changeFeatures",
+            )
+
     def testMinMaxAfterChanges(self):
         """
         Tests retrieving field min and max value after making changes to the provider's features
diff --git a/tests/src/python/test_provider_postgres.py b/tests/src/python/test_provider_postgres.py
index c6cd57c785f7..818bf957139e 100644
--- a/tests/src/python/test_provider_postgres.py
+++ b/tests/src/python/test_provider_postgres.py
@@ -67,6 +67,8 @@
     QgsVectorLayerUtils,
     QgsWkbTypes,
     QgsSettingsTree,
+    QgsUnsetAttributeValue,
+    QgsFeatureSink,
 )
 from qgis.gui import QgsAttributeForm, QgsGui
 import unittest
@@ -4921,6 +4923,85 @@ def testAddFeatureExtraAttributes(self):
             "The PostgreSQL provider doesn't truncate extra attributes.",
         )
 
+    def testAddFeatureUnsetAttributes(self):
+        # changed from ProviderTestBase.testAddFeatureMissingAttributes: this
+        # layer differs from the standard source definition because
+        # of the 'qgis' default value set on the text fields
+
+        if not getattr(self, "getEditableLayer", None):
+            return
+
+        l = self.getEditableLayer()
+        self.assertTrue(l.isValid())
+
+        f1 = QgsFeature()
+        f1.setAttributes(
+            [
+                6,
+                -220,
+                QgsUnsetAttributeValue(),
+                "String",
+                "15",
+                NULL,
+                NULL,
+                NULL,
+            ]
+        )
+        f1.setGeometry(QgsGeometry.fromWkt("Point (-72.345 71.987)"))
+
+        f2 = QgsFeature()
+        f2.setAttributes(
+            [
+                7,
+                QgsUnsetAttributeValue(),
+                "Coconut",
+                "CoCoNut",
+                "13",
+                NULL,
+                NULL,
+                NULL,
+            ]
+        )
+
+        if (
+            l.dataProvider().capabilities()
+            & QgsVectorDataProvider.Capability.AddFeatures
+        ):
+            # expect success
+            result, added = l.dataProvider().addFeatures(
+                [f1, f2], QgsFeatureSink.Flag.FastInsert
+            )
+            self.assertTrue(
+                result,
+                "Provider reported AddFeatures capability, but returned False to addFeatures using QgsUnsetAttributeValues",
+            )
+            self.assertEqual(l.dataProvider().featureCount(), 7)
+
+            features = [f for f in l.dataProvider().getFeatures()]
+            self.assertEqual(len(features), 7)
+            f6 = [f for f in features if f[0] == 6][0]
+            f7 = [f for f in features if f[0] == 7][0]
+            self.assertEqual(f6[1], -220)
+            self.assertEqual(f6[2], "qgis")
+            self.assertEqual(f6[3], "String")
+            self.assertEqual(f6[4], "15")
+            self.assertEqual(f6[5], NULL)
+            self.assertEqual(f6[6], NULL)
+            self.assertEqual(f6[7], NULL)
+
+            self.assertTrue(
+                isinstance(f7[1], QgsUnsetAttributeValue)
+                or f7[1] == NULL
+                or str(f7[1]) == "",
+                f"Expected null/unset value, got {f7[1]}",
+            )
+            self.assertEqual(f7[2], "Coconut")
+            self.assertEqual(f7[3], "CoCoNut")
+            self.assertEqual(f7[4], "13")
+            self.assertEqual(f7[5], NULL)
+            self.assertEqual(f7[6], NULL)
+            self.assertEqual(f7[7], NULL)
+
     def testAddFeatureMissingAttributes(self):
         if not getattr(self, "getEditableLayer", None):
             return
diff --git a/tests/src/python/test_qgsprocessinginplace.py b/tests/src/python/test_qgsprocessinginplace.py
index 366ac9d5552b..cf8c2d74c04f 100644
--- a/tests/src/python/test_qgsprocessinginplace.py
+++ b/tests/src/python/test_qgsprocessinginplace.py
@@ -1132,10 +1132,6 @@ def test_unique_constraints(self):
             alg, parameters, context=context, feedback=feedback, raise_exceptions=True
         )
 
-        pks = set()
-        for f in gpkg_layer.getFeatures():
-            pks.add(f.attribute(0))
-
         self.assertTrue(gpkg_layer.commitChanges())
 
     def test_regenerate_fid(self):