diff --git a/swh/indexer/metadata_dictionary.py b/swh/indexer/metadata_dictionary.py
--- a/swh/indexer/metadata_dictionary.py
+++ b/swh/indexer/metadata_dictionary.py
@@ -372,6 +372,14 @@
         except xml.parsers.expat.ExpatError:
             self.log.warning('Error parsing XML from %s', self.log_suffix)
             return None
+        except UnicodeDecodeError:
+            self.log.warning('Error unidecoding XML from %s', self.log_suffix)
+            return None
+        except (LookupError, ValueError):
+            # unknown encoding or multi-byte encoding
+            self.log.warning('Error detecting XML encoding from %s',
+                             self.log_suffix)
+            return None
         metadata = self.translate_dict(d, normalize=False)
         metadata[SCHEMA_URI+'codeRepository'] = self.parse_repositories(d)
         metadata[SCHEMA_URI+'license'] = self.parse_licenses(d)
diff --git a/swh/indexer/tests/test_metadata.py b/swh/indexer/tests/test_metadata.py
--- a/swh/indexer/tests/test_metadata.py
+++ b/swh/indexer/tests/test_metadata.py
@@ -629,6 +629,7 @@
         expected_warning = (
             'WARNING:swh.indexer.metadata_dictionary.MavenMapping:'
             'Error parsing XML from foo')
+
         raw_content = b"""
         <project>"""
         with self.assertLogs('swh.indexer.metadata_dictionary',
@@ -636,6 +637,7 @@
             result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
             self.assertEqual(cm.output, [expected_warning])
         self.assertEqual(result, None)
+
         raw_content = b"""
         """
         with self.assertLogs('swh.indexer.metadata_dictionary',
@@ -644,6 +646,43 @@
             self.assertEqual(cm.output, [expected_warning])
         self.assertEqual(result, None)
 
+    def test_compute_metadata_maven_unknown_encoding(self):
+        expected_warning = (
+            'WARNING:swh.indexer.metadata_dictionary.MavenMapping:'
+            'Error detecting XML encoding from foo')
+
+        raw_content = b"""<?xml version="1.0" encoding="foo"?>
+        <project>
+        </project>"""
+        with self.assertLogs('swh.indexer.metadata_dictionary',
+                             level='WARNING') as cm:
+            result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
+            self.assertEqual(cm.output, [expected_warning])
+        self.assertEqual(result, None)
+
+        raw_content = b"""<?xml version="1.0" encoding="UTF-7"?>
+        <project>
+        </project>"""
+        with self.assertLogs('swh.indexer.metadata_dictionary',
+                             level='WARNING') as cm:
+            result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
+            self.assertEqual(cm.output, [expected_warning])
+        self.assertEqual(result, None)
+
+    def test_compute_metadata_maven_invalid_encoding(self):
+        expected_warning = (
+            'WARNING:swh.indexer.metadata_dictionary.MavenMapping:'
+            'Error unidecoding XML from foo')
+
+        raw_content = b"""<?xml version="1.0" encoding="UTF-8"?>
+        <foo\xe5ct>
+        </foo>"""
+        with self.assertLogs('swh.indexer.metadata_dictionary',
+                             level='WARNING') as cm:
+            result = MAPPINGS["MavenMapping"]('foo').translate(raw_content)
+            self.assertEqual(cm.output, [expected_warning])
+        self.assertEqual(result, None)
+
     def test_compute_metadata_maven_minimal(self):
         raw_content = b"""
         <project>