diff --git a/plugins/generic/datacite/filter/DataciteXmlFilter.php b/plugins/generic/datacite/filter/DataciteXmlFilter.php
index f8e72bd1769..101ae301ce7 100644
--- a/plugins/generic/datacite/filter/DataciteXmlFilter.php
+++ b/plugins/generic/datacite/filter/DataciteXmlFilter.php
@@ -210,7 +210,7 @@ public function &process(&$pubObject)
         // Dates
         $rootNode->appendChild($this->createDatesNode($doc, $issue, $article, $publication, $galley, $galleyFile, $publicationDate));
         // Language
-        $rootNode->appendChild($node = $doc->createElementNS($deployment->getNamespace(), 'language', LocaleConversion::getIso1FromLocale($objectLocalePrecedence[0])));
+        $rootNode->appendChild($node = $doc->createElementNS($deployment->getNamespace(), 'language', str_replace(['_', '@'], '-', $objectLocalePrecedence[0])));
         // Resource Type
         $resourceTypeNode = $this->createResourceTypeNode($doc, $issue, $article, $galley, $galleyFile);
         if ($resourceTypeNode) {
diff --git a/plugins/generic/dublinCoreMeta/DublinCoreMetaPlugin.php b/plugins/generic/dublinCoreMeta/DublinCoreMetaPlugin.php
index d210864047b..ab9b444347f 100644
--- a/plugins/generic/dublinCoreMeta/DublinCoreMetaPlugin.php
+++ b/plugins/generic/dublinCoreMeta/DublinCoreMetaPlugin.php
@@ -17,7 +17,6 @@
 use APP\facades\Repo;
 use APP\template\TemplateManager;
 use PKP\core\PKPApplication;
-use PKP\i18n\LocaleConversion;
 use PKP\plugins\GenericPlugin;
 use PKP\plugins\Hook;
 
@@ -84,7 +83,7 @@ public function articleView($hookName, $args)
         if ($supportingAgencies = $publication->getData('supportingAgencies')) {
             foreach ($supportingAgencies as $locale => $localeSupportingAgencies) {
                 foreach ($localeSupportingAgencies as $i => $supportingAgency) {
-                    $templateMgr->addHeader('dublinCoreSponsor' . $locale . $i++, '<meta name="DC.Contributor.Sponsor" xml:lang="' . htmlspecialchars(LocaleConversion::getIso1FromLocale($locale)) . '" content="' . htmlspecialchars($supportingAgency) . '"/>');
+                    $templateMgr->addHeader('dublinCoreSponsor' . $locale . $i++, '<meta name="DC.Contributor.Sponsor" xml:lang="' . htmlspecialchars(str_replace(['_', '@'], '-', $locale)) . '" content="' . htmlspecialchars($supportingAgency) . '"/>');
                 }
             }
         }
@@ -92,7 +91,7 @@ public function articleView($hookName, $args)
         if ($coverages = $publication->getData('coverage')) {
             foreach ($coverages as $locale => $coverage) {
                 if ($coverage != '') {
-                    $templateMgr->addHeader('dublinCoreCoverage' . $locale, '<meta name="DC.Coverage" xml:lang="' . htmlspecialchars(LocaleConversion::getIso1FromLocale($locale)) . '" content="' . htmlspecialchars(strip_tags($coverage)) . '"/>');
+                    $templateMgr->addHeader('dublinCoreCoverage' . $locale, '<meta name="DC.Coverage" xml:lang="' . htmlspecialchars(str_replace(['_', '@'], '-', $locale)) . '" content="' . htmlspecialchars(strip_tags($coverage)) . '"/>');
                 }
             }
         }
@@ -116,7 +115,7 @@ public function articleView($hookName, $args)
         $abstracts = $publication->getData('abstract') ?: [];
         foreach ($abstracts as $locale => $abstract) {
             if ($abstract != '') {
-                $templateMgr->addHeader('dublinCoreAbstract' . $locale, '<meta name="DC.Description" xml:lang="' . htmlspecialchars(LocaleConversion::getIso1FromLocale($locale)) . '" content="' . htmlspecialchars(strip_tags($abstract)) . '"/>');
+                $templateMgr->addHeader('dublinCoreAbstract' . $locale, '<meta name="DC.Description" xml:lang="' . htmlspecialchars(str_replace(['_', '@'], '-', $locale)) . '" content="' . htmlspecialchars(strip_tags($abstract)) . '"/>');
             }
         }
 
@@ -147,7 +146,7 @@ public function articleView($hookName, $args)
 
         $templateMgr->addHeader('dublinCoreUri', '<meta name="DC.Identifier.URI" content="' . $request->getDispatcher()->url($request, PKPApplication::ROUTE_PAGE, null, 'article', 'view', [$articleBestId], urlLocaleForPage: '') . '"/>');
 
-        $templateMgr->addHeader('dublinCoreLanguage', '<meta name="DC.Language" scheme="ISO639-1" content="' . substr($publicationLocale, 0, 2) . '"/>');
+        $templateMgr->addHeader('dublinCoreLanguage', '<meta name="DC.Language" scheme="ISO639-1" content="' . str_replace(['_', '@'], '-', $publicationLocale) . '"/>');
 
         if (($copyrightHolder = $publication->getData('copyrightHolder', $publicationLocale)) && ($copyrightYear = $publication->getData('copyrightYear'))) {
             $templateMgr->addHeader('dublinCoreCopyright', '<meta name="DC.Rights" content="' . htmlspecialchars(__('submission.copyrightStatement', ['copyrightHolder' => $copyrightHolder, 'copyrightYear' => $copyrightYear])) . '"/>');
@@ -173,14 +172,14 @@ public function articleView($hookName, $args)
         if ($subjects = $publication->getData('subjects')) {
             foreach ($subjects as $locale => $localeSubjects) {
                 foreach ($localeSubjects as $i => $subject) {
-                    $templateMgr->addHeader('dublinCoreSubject' . $locale . $i++, '<meta name="DC.Subject" xml:lang="' . htmlspecialchars(LocaleConversion::getIso1FromLocale($locale)) . '" content="' . htmlspecialchars($subject) . '"/>');
+                    $templateMgr->addHeader('dublinCoreSubject' . $locale . $i++, '<meta name="DC.Subject" xml:lang="' . htmlspecialchars(str_replace(['_', '@'], '-', $locale)) . '" content="' . htmlspecialchars($subject) . '"/>');
                 }
             }
         }
         if ($keywords = $publication->getData('keywords')) {
             foreach ($keywords as $locale => $localeKeywords) {
                 foreach ($localeKeywords as $i => $keyword) {
-                    $templateMgr->addHeader('dublinCoreKeyword' . $locale . $i++, '<meta name="DC.Subject" xml:lang="' . htmlspecialchars(LocaleConversion::getIso1FromLocale($locale)) . '" content="' . htmlspecialchars($keyword) . '"/>');
+                    $templateMgr->addHeader('dublinCoreKeyword' . $locale . $i++, '<meta name="DC.Subject" xml:lang="' . htmlspecialchars(str_replace(['_', '@'], '-', $locale)) . '" content="' . htmlspecialchars($keyword) . '"/>');
                 }
             }
         }
@@ -188,7 +187,7 @@ public function articleView($hookName, $args)
         $templateMgr->addHeader('dublinCoreTitle', '<meta name="DC.Title" content="' . htmlspecialchars($publication->getLocalizedFullTitle($publicationLocale)) . '"/>');
         foreach ($publication->getFullTitles() as $locale => $title) {
             if ($title != '' && $locale != $publicationLocale) {
-                $templateMgr->addHeader('dublinCoreAltTitle' . $locale, '<meta name="DC.Title.Alternative" xml:lang="' . htmlspecialchars(LocaleConversion::getIso1FromLocale($locale)) . '" content="' . htmlspecialchars($title) . '"/>');
+                $templateMgr->addHeader('dublinCoreAltTitle' . $locale, '<meta name="DC.Title.Alternative" xml:lang="' . htmlspecialchars(str_replace(['_', '@'], '-', $locale)) . '" content="' . htmlspecialchars($title) . '"/>');
             }
         }
 
@@ -196,7 +195,7 @@ public function articleView($hookName, $args)
         if ($types = $publication->getData('type')) {
             foreach ($types as $locale => $type) {
                 if ($type != '') {
-                    $templateMgr->addHeader('dublinCoreType' . $locale, '<meta name="DC.Type" xml:lang="' . htmlspecialchars(LocaleConversion::getIso1FromLocale($locale)) . '" content="' . htmlspecialchars(strip_tags($type)) . '"/>');
+                    $templateMgr->addHeader('dublinCoreType' . $locale, '<meta name="DC.Type" xml:lang="' . htmlspecialchars(str_replace(['_', '@'], '-', $locale)) . '" content="' . htmlspecialchars(strip_tags($type)) . '"/>');
                 }
             }
         }