diff --git a/.ci/test_blocklist_qt6.txt b/.ci/test_blocklist_qt6.txt
index e04e26a9150..1f3baf37fa0 100644
--- a/.ci/test_blocklist_qt6.txt
+++ b/.ci/test_blocklist_qt6.txt
@@ -7,7 +7,6 @@ test_core_expression
 test_core_field
 test_core_geometry
 test_core_labelingengine
-test_core_layertree
 test_core_layout
 test_core_layouthtml
 test_core_layoutlabel
@@ -19,18 +18,14 @@ test_core_layouttable
 test_core_legendrenderer
 test_core_maprendererjob
 test_core_maprotation
-test_core_meshlayer
 test_core_networkaccessmanager
 test_core_ogcutils
 test_core_pallabeling
 test_core_pointpatternfillsymbol
-test_core_project
-test_core_projectstorage
 test_core_rasterlayer
 test_core_tiledownloadmanager
 test_core_vectortilelayer
 test_core_geometry_pointxy
-test_analysis_processingalgspt1
 test_analysis_processingalgspt2
 
 # block list
diff --git a/src/core/qgsxmlutils.cpp b/src/core/qgsxmlutils.cpp
index 9be5e13906d..26e1a2e83c0 100644
--- a/src/core/qgsxmlutils.cpp
+++ b/src/core/qgsxmlutils.cpp
@@ -169,7 +169,7 @@ QDomElement QgsXmlUtils::writeVariant( const QVariant &value, QDomDocument &doc
 
     case QVariant::Char:
       element.setAttribute( QStringLiteral( "type" ), QVariant::typeToName( value.type() ) );
-      element.setAttribute( QStringLiteral( "value" ), value.isNull() ? QString() : value.toString() );
+      element.setAttribute( QStringLiteral( "value" ), value.isNull() || value.toChar().isNull() ? QString() : QString( value.toChar() ) );
       break;
 
     case QVariant::Color: