diff --git a/idhub/admin/forms.py b/idhub/admin/forms.py
index 5476507..b8fcec4 100644
--- a/idhub/admin/forms.py
+++ b/idhub/admin/forms.py
@@ -189,7 +189,7 @@ class ImportForm(forms.Form):
         cred = VerificableCredential(
             verified=False,
             user=user,
-            csv_data=json.dumps(row),
+            csv_data=json.dumps(row, default=str),
             issuer_did=self._did,
             schema=self._schema,
             eidas1_did=self._eidas1
diff --git a/requirements.txt b/requirements.txt
index 27dd8c6..db0d96e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -27,4 +27,5 @@ uharfbuzz==0.38.0
 fontTools==4.47.0
 weasyprint==60.2
 ujson==5.9.0
+openpyxl==3.1.2
 ./didkit-0.3.2-cp311-cp311-manylinux_2_34_x86_64.whl