diff --git a/src/providers/postgres/qgspostgresprovider.cpp b/src/providers/postgres/qgspostgresprovider.cpp
index de585580ec6a..deb2b24b91b8 100644
--- a/src/providers/postgres/qgspostgresprovider.cpp
+++ b/src/providers/postgres/qgspostgresprovider.cpp
@@ -3479,7 +3479,11 @@ bool QgsPostgresProvider::changeFeatures( const QgsChangedAttributesMap &attr_ma
 
         result = conn->PQexecPrepared( QStringLiteral( "updatefeature" ), params );
         if ( result.PQresultStatus() != PGRES_COMMAND_OK && result.PQresultStatus() != PGRES_TUPLES_OK )
+        {
+          conn->rollback();
+          conn->PQexecNR( QStringLiteral( "DEALLOCATE updatefeature" ) );
           throw PGException( result );
+        }
 
         conn->PQexecNR( QStringLiteral( "DEALLOCATE updatefeature" ) );
       }
diff --git a/tests/src/python/test_provider_postgres.py b/tests/src/python/test_provider_postgres.py
index 4ff9af6241c6..2d3a36d257f5 100644
--- a/tests/src/python/test_provider_postgres.py
+++ b/tests/src/python/test_provider_postgres.py
@@ -2065,6 +2065,18 @@ def testReadExtentOnTable(self):
         vl2.readLayerXml(elem, QgsReadWriteContext())
         self.assertEqual(vl2.extent(), originalExtent)
 
+    def testPreparedFailure(self):
+        """Test error from issue GH #45100"""
+
+        layer = self.getEditableLayerWithCheckConstraint()
+        self.assertTrue(layer.startEditing())
+        old_value = layer.getFeature(1).attribute('i_will_fail_on_no_name')
+        layer.changeAttributeValue(1, 1, 'no name')
+        layer.changeGeometry(1, QgsGeometry.fromWkt('point(7 45)'))
+        self.assertFalse(layer.commitChanges())
+        layer.changeAttributeValue(1, 1, old_value)
+        self.assertTrue(layer.commitChanges())
+
     def testDeterminePkey(self):
         """Test primary key auto-determination"""