diff --git a/.github/workflows/docs.yaml b/.github/workflows/docs.yaml
index 0c5ff2aa3..dc50c7ec7 100644
--- a/.github/workflows/docs.yaml
+++ b/.github/workflows/docs.yaml
@@ -21,7 +21,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v2
         with:
-          python-version: 3.9
+          python-version: 3.13
       - name: Update package index
         run: sudo apt-get update
       - name: Install mpi libs
diff --git a/armi/nucDirectory/nuclideBases.py b/armi/nucDirectory/nuclideBases.py
index d9e1130fc..2821e116d 100644
--- a/armi/nucDirectory/nuclideBases.py
+++ b/armi/nucDirectory/nuclideBases.py
@@ -800,22 +800,6 @@ def getMcnpId(self):
         """
         return "{0:d}000".format(self.z)
 
-    def getAAAZZZSId(self):
-        """Gets the AAAZZZS ID for a few elements.
-
-        Notes
-        -----
-        the natural nuclides 'C' and 'V' do not have isotopic nuclide data for MC2 so sometimes they tag along in the
-        list of active nuclides. This method is designed to fail in the same as if there was not getAAAZZZSId method
-        defined.
-        """
-        if self.element.symbol == "C":
-            return "120060"
-        elif self.element.symbol == "V":
-            return "510230"
-        else:
-            return None
-
     def getMcc2Id(self):
         """Return the MC2-2 nuclide identification label based on the ENDF/B-V.2 cross section library."""
         return self.mcc2id
@@ -1442,6 +1426,8 @@ def addGlobalNuclide(nuclide: NuclideBase):
                 f"{nuclide} with McnpId {nuclide.getMcnpId()} has already been added and cannot be duplicated."
             )
         byMcnpId[nuclide.getMcnpId()] = nuclide
+    if not isinstance(nuclide, (NaturalNuclideBase, LumpNuclideBase, DummyNuclideBase)):
+        # There are no AZS ID for elements / natural nuclides, or ficticious lump or dummy nuclides
         byAAAZZZSId[nuclide.getAAAZZZSId()] = nuclide
 
 
diff --git a/armi/nucDirectory/tests/test_nuclideBases.py b/armi/nucDirectory/tests/test_nuclideBases.py
index 1ef1b5900..066d0f5b7 100644
--- a/armi/nucDirectory/tests/test_nuclideBases.py
+++ b/armi/nucDirectory/tests/test_nuclideBases.py
@@ -466,11 +466,9 @@ def test_AAAZZZSNameGenerator(self):
             :tests: R_ARMI_ND_ISOTOPES
         """
         referenceNucNames = [
-            ("C", "120060"),
+            ("C12", "120060"),
             ("U235", "2350920"),
             ("AM242M", "2420951"),
-            ("LFP35", None),
-            ("DUMP1", None),
         ]
 
         for nucName, refAaazzzs in referenceNucNames:
diff --git a/armi/physics/neutronics/crossSectionGroupManager.py b/armi/physics/neutronics/crossSectionGroupManager.py
index 1eca9a382..f049890bb 100644
--- a/armi/physics/neutronics/crossSectionGroupManager.py
+++ b/armi/physics/neutronics/crossSectionGroupManager.py
@@ -63,7 +63,6 @@
 from armi.physics.neutronics.const import CONF_CROSS_SECTION
 from armi.reactor import flags
 from armi.reactor.components import basicShapes
-from armi.reactor.converters.blockConverters import stripComponents
 from armi.reactor.flags import Flags
 from armi.utils import safeCopy
 from armi.utils.units import C_TO_K, TRACE_NUMBER_DENSITY
@@ -710,6 +709,8 @@ def _makeRepresentativeBlock(self):
 
     def _getNucTempHelper(self):
         """All candidate blocks are used in the average."""
+        from armi.reactor.converters.blockConverters import stripComponents
+
         nvt = np.zeros(len(self.allNuclidesInProblem))
         nv = np.zeros(len(self.allNuclidesInProblem))
         for block in self.getCandidateBlocks():
diff --git a/armi/reactor/__init__.py b/armi/reactor/__init__.py
index 3536b698c..85bddbb21 100644
--- a/armi/reactor/__init__.py
+++ b/armi/reactor/__init__.py
@@ -16,36 +16,6 @@
 The reactor package houses the data model used in ARMI to represent the reactor during its
 simulation. It contains definitions of the reactor, assemblies, blocks, components, etc.
 
-The key classes of the reactor package are shown below:
-
-.. _reactor-class-diagram:
-
-.. pyreverse:: armi.reactor -A -k --ignore=
-               assemblyParameters.py,
-               basicShapes.py,
-               blockParameters.py,
-               blueprints,
-               complexShapes.py,
-               componentParameters.py,
-               converters,
-               excoreStructure.py,
-               flags.py,
-               geometry.py,
-               grids.py,
-               parameters,
-               plugins.py,
-               reactorParameters.py,
-               shapes.py,
-               spentFuelPool.py,
-               tests,
-               volumetricShapes.py,
-               zones.py
-    :align: center
-    :alt: Reactor class diagram
-    :width: 90%
-
-    Class inheritance diagram for :py:mod:`armi.reactor`.
-
 See :doc:`/developer/index`.
 """
 
diff --git a/armi/reactor/blueprints/componentBlueprint.py b/armi/reactor/blueprints/componentBlueprint.py
index 54676cbea..838c55253 100644
--- a/armi/reactor/blueprints/componentBlueprint.py
+++ b/armi/reactor/blueprints/componentBlueprint.py
@@ -378,10 +378,18 @@ def _constructMaterial(self, blueprint, matMods):
             try:
                 # update material with updated input params from blueprints file.
                 mat.applyInputParams(**matMods)
-            except TypeError:
-                # This component does not accept material modification inputs of the names passed in
-                # Keep going since the modification could work for another component
-                pass
+            except TypeError as ee:
+                errorMessage = ee.args[0]
+                if "got an unexpected keyword argument" in errorMessage:
+                    # This component does not accept material modification inputs of the names passed in
+                    # Keep going since the modification could work for another component
+                    pass
+                else:
+                    raise ValueError(
+                        f"Something went wrong in applying the material modifications {matMods} "
+                        f"to component {self.name}.\n"
+                        f"Error message is: \n{errorMessage}."
+                    )
 
         expandElementals(mat, blueprint)
 
diff --git a/armi/reactor/blueprints/tests/test_materialModifications.py b/armi/reactor/blueprints/tests/test_materialModifications.py
index 52ada251e..eaccb00db 100644
--- a/armi/reactor/blueprints/tests/test_materialModifications.py
+++ b/armi/reactor/blueprints/tests/test_materialModifications.py
@@ -259,7 +259,7 @@ def test_filterMaterialInput(self):
 
     def test_invalidMatModName(self):
         """
-        This test shows proves that we can detect invalid material modification
+        This test shows that we can detect invalid material modification
         names when they are specified on an assembly blueprint. We happen to know
         that ZR_wt_frac is a valid modification for the UZr material class, so we
         use that in the first call to prove that things initially work fine.
@@ -299,6 +299,35 @@ def test_invalidMatModName(self):
         """
             )
 
+    def test_invalidMatModType(self):
+        """
+        This test shows that we can detect material modifications that are invalid
+        because of their values, not just their names.
+        We happen to know that ZR_wt_frac is a valid modification for UZr, so we
+        use that in the first call to prove that things initially work fine.
+        """
+        a = self.loadUZrAssembly(
+            """
+        material modifications:
+            ZR_wt_frac: [1]
+        """
+        )
+        # just to prove that the above works fine before we modify it
+        self.assertAlmostEqual(a[0][0].getMassFrac("ZR"), 1)
+
+        with self.assertRaises(ValueError) as ee:
+            a = self.loadUZrAssembly(
+                """
+        material modifications:
+            ZR_wt_frac: [this_is_a_value_of_incompatible_type]
+        """
+            )
+
+            self.assertIn(
+                "Something went wrong in applying the material modifications",
+                ee.args[0],
+            )
+
     def test_matModsUpTheMRO(self):
         """
         Make sure that valid/invalid material modifications are searched up
diff --git a/armi/runLog.py b/armi/runLog.py
index 484672dfd..b7393bd66 100644
--- a/armi/runLog.py
+++ b/armi/runLog.py
@@ -572,7 +572,7 @@ def __init__(self, *args, **kwargs):
         handler.setFormatter(form)
         self.addHandler(handler)
 
-    def log(self, msgType, msg, single=False, label=None, **kwargs):
+    def log(self, msgType, msg, single=False, label=None, *args, **kwargs):
         """
         This is a wrapper around logger.log() that does most of the work.
 
diff --git a/doc/conf.py b/doc/conf.py
index aa8745d2c..9a5d4be47 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -24,6 +24,7 @@
 All configuration values have a default; values that are commented out
 serve to show the default.
 """
+
 # ruff: noqa: E402
 import datetime
 import inspect
@@ -35,7 +36,7 @@
 import sys
 import warnings
 
-import sphinx_rtd_theme
+import sphinx_rtd_theme  # noqa: F401
 from docutils import nodes, statemachine
 from docutils.parsers.rst import Directive, directives
 from sphinx.domains.python import PythonDomain
@@ -97,14 +98,13 @@ class ExecDirective(Directive):
 
     def run(self):
         try:
-            code = inspect.cleandoc(
-                """
-            def usermethod():
-                {}
-            """
-            ).format("\n    ".join(self.content))
-            exec(code)
-            result = locals()["usermethod"]()
+            # clean the content, then put back into a list
+            cleancode = inspect.cleandoc("\n".join(self.content)).split("\n")
+            code = "def usermethod():\n    " + "\n    ".join(cleancode)
+            globals = {}
+            exec(code, globals)
+
+            result = globals["usermethod"]()
 
             if result is None:
                 raise self.error(
@@ -119,9 +119,7 @@ def usermethod():
         except Exception as e:
             docname = self.state.document.settings.env.docname
             raise self.error(
-                "Unable to execute embedded doc code at {}:{} ... {}\n{}".format(
-                    docname, self.lineno, datetime.datetime.now(), str(e)
-                )
+                f"Unable to execute embedded doc code at {docname}:{self.lineno}\n{str(e)}"
             )
 
 
@@ -337,6 +335,12 @@ def setup(app):
 # looking for source files.
 exclude_patterns = [
     "**.ipynb",
+    "**/Python27*",
+    "**/ccl*",
+    "gallery/**/*.ipynb",  # prevent sphinx-gallery from causing duplicate source file errors
+    "gallery/**/*.md5",
+    "gallery/**/*.zip",
+    "gallery/**/*.json",
     "**.ipynb_checkpoints",
     "**/ccl*",
     "**/Python27*",
@@ -389,9 +393,6 @@ def setup(app):
     "titles_only": False,
 }
 
-# Add any paths that contain custom themes here, relative to this directory.
-html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
-
 # as long as this file @import's the theme's main css it won't break anything
 html_style = "css/theme_fixes.css"
 
diff --git a/doc/gallery-src/framework/run_chartOfNuclides.py b/doc/gallery-src/framework/run_chartOfNuclides.py
index f0818d7e4..5a4516ffc 100644
--- a/doc/gallery-src/framework/run_chartOfNuclides.py
+++ b/doc/gallery-src/framework/run_chartOfNuclides.py
@@ -22,7 +22,9 @@
 
     Our :ref:`extended tutorial for nuclides </tutorials/nuclide_demo.ipynb>` and
     detailed :py:mod:`nucDirectory docs <armi.nucDirectory>` may also be of interest.
+
 """
+
 import matplotlib.pyplot as plt
 
 from armi import configure
diff --git a/doc/gallery-src/framework/run_computeReactionRates.py b/doc/gallery-src/framework/run_computeReactionRates.py
index 1a7c2d52b..2c2578e2e 100644
--- a/doc/gallery-src/framework/run_computeReactionRates.py
+++ b/doc/gallery-src/framework/run_computeReactionRates.py
@@ -28,7 +28,7 @@
 from armi import configure, nuclideBases, settings
 from armi.materials import ht9, sodium, uZr
 from armi.nuclearDataIO.cccc import isotxs
-from armi.reactor import assemblies, blocks, blueprints, geometry, grids, reactors
+from armi.reactor import assemblies, blocks, geometry, grids, reactors
 from armi.reactor.components import Circle, DerivedShape, Hexagon
 from armi.reactor.flags import Flags
 from armi.tests import ISOAA_PATH
@@ -56,7 +56,9 @@ def createDummyReactor():
     Often, a reactor model like this is built directly from input files rather
     than from code as done here.
     """
-    bp = blueprints.Blueprints()
+    from armi.reactor.blueprints import Blueprints
+
+    bp = Blueprints()
     cs = settings.Settings()
 
     r = reactors.Reactor("Reactor", bp)
diff --git a/doc/gallery-src/framework/run_fuelManagement.py b/doc/gallery-src/framework/run_fuelManagement.py
index a55adcab2..7512f8c17 100644
--- a/doc/gallery-src/framework/run_fuelManagement.py
+++ b/doc/gallery-src/framework/run_fuelManagement.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 """
 Fuel management in a LWR.
+=========================
 
 Demo of locating and swapping assemblies in a core with Cartesian geometry. Given a burnup
 distribution, this swaps high burnup assemblies with low ones.
@@ -26,6 +27,7 @@
 ARMI to do fuel management. Thus, this example applies a dummy burnup distribution for
 demonstration purposes.
 """
+
 # Tell the gallery to feature the 2nd image
 # sphinx_gallery_thumbnail_number = 2
 import math
diff --git a/doc/release/0.5.rst b/doc/release/0.5.rst
index 130031b1f..f96c79b23 100644
--- a/doc/release/0.5.rst
+++ b/doc/release/0.5.rst
@@ -28,8 +28,9 @@ Bug Fixes
 
 Quality Work
 ------------
-#. Adding PDF versions of the ARMI docs. (`PR#2072 <https://github.com/terrapower/armi/pull/2072>`_)
 #. Open-Sourcing the ARMI requirements. (`PR#2076 <https://github.com/terrapower/armi/pull/2076>`_)
+#. Update docs build to occur with python 3.13 and updated docs dependencies. (`PR#2050 <https://github.com/terrapower/armi/pull/2050>`_)
+#. Adding PDF versions of the ARMI docs. (`PR#2072 <https://github.com/terrapower/armi/pull/2072>`_)
 #. TBD
 
 
diff --git a/pyproject.toml b/pyproject.toml
index e18eb030b..2c273a7c3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -92,33 +92,30 @@ test = [
 docs = [
 #######################################################################
 # These are most specified that usual, because Sphinx docs seem to be
-# quite fragile limited <7 by sphinx-rtd-theme at the moment.
+# quite fragile.
 #
-# sphinx-rtd-theme requires docutils <0.19 but sphinx dropped support
-# for 0.18 in 6.0.0 so we're stuck at these versions.
-#
-# We are only building our docs with Python 3.9.
+# We are only building our docs with Python 3.13.
 #######################################################################
-    "Sphinx==5.3.0", # central library used to build our docs
-    "docutils==0.18.1", # Needed by sphinx-rtd-them
-    "sphinx-rtd-theme==1.2.2", # Read-The-Docs theme for Sphinx
-    "nbsphinx==0.9.2", # Parses Jupyter notebooks
+    "docutils==0.21.2", # Needed by sphinx-rtd-them
+    "ipykernel", # iPython kernel to run Jupyter notebooks
+    "Jinja2", # Used in numpydoc and nbconvert
+    "nbsphinx", # Parses Jupyter notebooks
     "nbsphinx-link==1.3.0", # Adds Jupyter NBs to Sphinx source root
+    "nbsphinx==0.9.2", # Parses Jupyter notebooks
+    "pandoc", # Must be in the path (to convert file formats)
+    "pylint", # Generates UML diagrams
+    "setuptools",  # needed for conf.py tooling
     "sphinx-gallery==0.13.0", # Builds an HTML version of a Python script and puts it into a gallery
-    "sphinxcontrib-apidoc==0.3.0", # More easily document our API
-    "sphinxext-opengraph==0.8.2", # Generates OpenGraph metadata to make good-looking cards on social media
-    "sphinx-needs==2.1.0", # Requirements traceability matrices for QA
+    "sphinx-needs==4.1.0", # Requirements traceability matrices for QA
+    "sphinx-rtd-theme==3.0.2", # Read-The-Docs theme for Sphinx
+    "sphinx-simplepdf==1.6.0", # Used to make PDF versions of the docs
     "sphinx-test-reports",
-    "sphinxcontrib-plantuml==0.25", # UML support in sphinx-needs
-    "unittest-xml-reporting",
-    "pandoc", # Must be in the path (to convert file formats)
-    "ipykernel==6.25.1", # iPython kernel to run Jupyter notebooks
-    "pylint==2.17.5", # Generates UML diagrams
-    "Jinja2==3.0.3", # Used in numpydoc and nbconvert
+    "Sphinx==8.1.3", # central library used to build our docs
+    "sphinxcontrib-apidoc==0.5.0", # More easily document our API
     "sphinxcontrib-jquery==4.1", # Handle missing jquery errors
-    "jupyter-contrib-nbextensions", # A collections of JS extensions for jupyter notebooks
-    "lxml<5.0.0", # Needed because the dep above is no longer an active project
-    "sphinx-simplepdf==1.6.0", # Used to make PDF versions of the docs
+    "sphinxcontrib-plantuml==0.30", # UML support in sphinx-needs
+    "sphinxext-opengraph==0.8.2", # Generates OpenGraph metadata to make cards for social media
+    "unittest-xml-reporting",
 ]
 
 [project.scripts]