diff --git a/src/DIRAC/Core/Utilities/Graphs/Graph.py b/src/DIRAC/Core/Utilities/Graphs/Graph.py
index 2162dd8d968..faf564222ed 100644
--- a/src/DIRAC/Core/Utilities/Graphs/Graph.py
+++ b/src/DIRAC/Core/Utilities/Graphs/Graph.py
@@ -6,6 +6,7 @@
 """
 
 import datetime
+import importlib
 import time
 import os
 
@@ -274,18 +275,13 @@ def makeGraph(self, data, *args, **kw):
         for i in range(nPlots):
             plot_type = plot_prefs[i]["plot_type"]
             try:
-                # TODO: Remove when we moved to python3
-                exec(f"import {plot_type}")
-            except ImportError:
-                print("Trying to use python like import")
-                try:
-                    exec(f"from . import  {plot_type}")
-                except ImportError as x:
-                    print(f"Failed to import graph type {plot_type}: {str(x)}")
-                    return None
+                plotModule = importlib.import_module(f"DIRAC.Core.Utilities.Graphs.{plot_type}")
+            except ModuleNotFoundError as x:
+                print(f"Failed to import graph type {plot_type}: {str(x)}")
+                return None
 
             ax = plot_axes[i]
-            plot = eval(f"{plot_type}.{plot_type}(graphData[i],ax,plot_prefs[i])")
+            plot = getattr(plotModule, plot_type)(graphData[i], ax, plot_prefs[i])
             plot.draw()
 
         if DEBUG:
diff --git a/src/DIRAC/tests/Utilities/plots.py b/src/DIRAC/tests/Utilities/plots.py
index 52001f76b41..fbc6f3d5afd 100644
--- a/src/DIRAC/tests/Utilities/plots.py
+++ b/src/DIRAC/tests/Utilities/plots.py
@@ -1,6 +1,8 @@
 # pylint: disable=protected-access
+import glob
 import math
 import operator
+import os
 from functools import reduce
 
 from PIL import Image
@@ -24,3 +26,37 @@ def compare(file1Path, file2Path):
     h2 = image2.histogram()
     rms = math.sqrt(reduce(operator.add, map(lambda a, b: (a - b) ** 2, h1, h2)) / len(h1))
     return rms
+
+
+def referenceImages(directory, stem):
+    """Return every reference image available for a given plot.
+
+    The primary reference is ``<stem>.png``. Additional references may be added
+    as ``<stem>.<tag>.png`` (for example ``histogram1.mpl-3.10.png``) when a new
+    matplotlib version renders a plot slightly differently. Keeping several
+    references side by side means a plot is accepted against any supported
+    plotting-stack version, so an upgrade only needs an extra reference image
+    rather than replacing the existing one (which would break older versions).
+
+    :param str directory: Directory holding the reference images.
+    :param str stem: Base name of the plot, without extension.
+    :return: Sorted list of reference image paths.
+    """
+    paths = glob.glob(os.path.join(directory, f"{stem}.png"))
+    paths += glob.glob(os.path.join(directory, f"{stem}.*.png"))
+    return sorted(paths)
+
+
+def compareToReferences(generatedPath, referencePaths):
+    """Compare a generated plot against several candidate reference images.
+
+    :param str generatedPath: Path to the freshly generated plot.
+    :param referencePaths: Iterable of reference image paths to compare against.
+
+    :return: The smallest RMS obtained against any of the references, so a plot
+        is accepted as soon as it is identical (rms == 0.0) to one of them.
+    """
+    referencePaths = list(referencePaths)
+    if not referencePaths:
+        raise ValueError(f"No reference images provided for {generatedPath}")
+    return min(compare(generatedPath, reference) for reference in referencePaths)
diff --git a/tests/Integration/AccountingSystem/Test_Plots.py b/tests/Integration/AccountingSystem/Test_Plots.py
index 2d3829b8604..347bb170b88 100644
--- a/tests/Integration/AccountingSystem/Test_Plots.py
+++ b/tests/Integration/AccountingSystem/Test_Plots.py
@@ -20,7 +20,7 @@
     generateErrorMessagePlot,
 )
 
-from DIRAC.tests.Utilities.plots import compare
+from DIRAC.tests.Utilities.plots import compareToReferences, referenceImages
 
 plots_directory = os.path.join(os.path.dirname(__file__), "plots")
 filename = "plot.png"
@@ -34,7 +34,7 @@ def test_histogram():
     res = generateHistogram(filename, [2, 2, 3, 4, 5, 5], {})
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "histogram1.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "histogram1"))
     assert res == 0.0
 
     res = generateHistogram(
@@ -42,13 +42,13 @@ def test_histogram():
     )
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "histogram2.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "histogram2"))
     assert res == 0.0
 
     res = generateHistogram(filename, [{"a": [1]}, {"b": [2, 3, 3, 5, 5]}], {})
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "histogram3.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "histogram3"))
     assert res == 0.0
 
 
@@ -104,7 +104,7 @@ def test_stackedlineplots():
 
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "stackedline.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "stackedline"))
     assert res == 0.0
 
 
@@ -115,7 +115,7 @@ def test_piechartplot():
     res = generatePiePlot(filename, {"a": 16.0, "b": 56.0, "c": 15, "d": 20}, {})
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "piechart.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "piechart"))
     assert res == 0.0
 
 
@@ -167,7 +167,7 @@ def test_cumulativeplot():
 
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "cumulativeplot.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "cumulativeplot"))
     assert res == 0.0
 
 
@@ -183,7 +183,7 @@ def test_qualityplot():
     )
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "qualityplot1.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "qualityplot1"))
     assert res == 0.0
 
     res = generateQualityPlot(
@@ -193,7 +193,7 @@ def test_qualityplot():
     )
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "qualityplot2.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "qualityplot2"))
     assert res == 0.0
 
 
@@ -269,7 +269,7 @@ def test_timestackedbarplot():
     )
     assert res["OK"] is True
 
-    res = compare(filename, os.path.join(plots_directory, "timedstackedbarplot.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "timedstackedbarplot"))
     assert res == 0.0
 
 
@@ -280,7 +280,7 @@ def test_nodataplot():
 
     res = generateNoDataPlot(filename, {}, {"title": "Test plot"})
     assert res["OK"] is True
-    res = compare(filename, os.path.join(plots_directory, "nodata.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "nodata"))
     assert res == 0.0
 
 
@@ -293,5 +293,5 @@ def test_error():
     with open(filename, "wb") as out:
         out.write(res)
 
-    res = compare(filename, os.path.join(plots_directory, "error.png"))
+    res = compareToReferences(filename, referenceImages(plots_directory, "error"))
     assert res == 0.0
diff --git a/tests/Integration/AccountingSystem/plots/cumulativeplot.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/cumulativeplot.mpl-3.11.0.png
new file mode 100644
index 00000000000..e2b7c5e4b58
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/cumulativeplot.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/error.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/error.mpl-3.11.0.png
new file mode 100644
index 00000000000..be5ef1bcc80
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/error.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/histogram1.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/histogram1.mpl-3.11.0.png
new file mode 100644
index 00000000000..ab416483dcf
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/histogram1.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/histogram2.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/histogram2.mpl-3.11.0.png
new file mode 100644
index 00000000000..3602194e2e9
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/histogram2.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/histogram3.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/histogram3.mpl-3.11.0.png
new file mode 100644
index 00000000000..cc92de65ad7
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/histogram3.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/nodata.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/nodata.mpl-3.11.0.png
new file mode 100644
index 00000000000..461f1f4bc71
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/nodata.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/piechart.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/piechart.mpl-3.11.0.png
new file mode 100644
index 00000000000..d746467866c
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/piechart.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/qualityplot1.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/qualityplot1.mpl-3.11.0.png
new file mode 100644
index 00000000000..15e008d9763
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/qualityplot1.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/qualityplot2.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/qualityplot2.mpl-3.11.0.png
new file mode 100644
index 00000000000..3d4d799a4a2
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/qualityplot2.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/stackedline.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/stackedline.mpl-3.11.0.png
new file mode 100644
index 00000000000..e1cdd8518f7
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/stackedline.mpl-3.11.0.png differ
diff --git a/tests/Integration/AccountingSystem/plots/timedstackedbarplot.mpl-3.11.0.png b/tests/Integration/AccountingSystem/plots/timedstackedbarplot.mpl-3.11.0.png
new file mode 100644
index 00000000000..5d6549ebf12
Binary files /dev/null and b/tests/Integration/AccountingSystem/plots/timedstackedbarplot.mpl-3.11.0.png differ
diff --git a/tests/Integration/DataManagementSystem/Test_UserMetadata.py b/tests/Integration/DataManagementSystem/Test_UserMetadata.py
index fffd0c20d4a..b5b00e4c743 100644
--- a/tests/Integration/DataManagementSystem/Test_UserMetadata.py
+++ b/tests/Integration/DataManagementSystem/Test_UserMetadata.py
@@ -122,8 +122,8 @@ def test_metaIndex(self):
         # meta show
         result = self.fc.getMetadataFields()
         self.assertTrue(result["OK"])
-        self.assertDictContainsSubset({"MetaInt6": "INT"}, result["Value"]["FileMetaFields"])
-        self.assertDictContainsSubset({"TestDirectory6": "INT"}, result["Value"]["DirectoryMetaFields"])
+        self.assertLessEqual({"MetaInt6": "INT"}.items(), result["Value"]["FileMetaFields"].items())
+        self.assertLessEqual({"TestDirectory6": "INT"}.items(), result["Value"]["DirectoryMetaFields"].items())
 
         # meta set
         metaDict6 = {"MetaInt6": 13}
@@ -147,7 +147,7 @@ def test_metaIndex(self):
         # API call only
         result = self.fc.getFileUserMetadata(self.lfn5)
         self.assertTrue(result["OK"])
-        self.assertDictContainsSubset({"MetaInt6": 13}, result["Value"])
+        self.assertLessEqual({"MetaInt6": 13}.items(), result["Value"].items())
         # file: expect a failure
         result = self.fc.getDirectoryUserMetadata(self.lfn5)
         self.assertFalse(result["OK"])
@@ -155,7 +155,7 @@ def test_metaIndex(self):
         # directory
         result = self.fc.getDirectoryUserMetadata(self.dir5)
         self.assertTrue(result["OK"])
-        self.assertDictContainsSubset({"TestDirectory6": 126}, result["Value"])
+        self.assertLessEqual({"TestDirectory6": 126}.items(), result["Value"].items())
 
         # finally remove
         # meta remove lfn5 MetaInt6