It is weird. the debug function highlights RunCommand acCmdSaveRecord but the record is saving just fine.
you got the error because Not In a List event is a Validation event. You don't put any code there to save the record, yet.
this is working without error:
' File MRR DLog skinny
Private Sub Combo53_NotInList(NewData As String, Response As Integer)
StrNew = NewData
strTmp = "Add '" & NewData & "' as a new category?"
If MsgBox(strTmp, vbYesNo + vbDefaultButton2 + vbQuestion, "Not in list") = vbYes Then
DoCmd.RunSQL "INSERT INTO tblCategory " _
& "(VendorName,Category) VALUES " _
& "(" & Chr(34) & Forms!frmMRRLog!SupplierName & Chr(34) & "," & Chr(34) & NewData & Chr(34) & ");"
'Neither fixed the issue, tried nothing and got same behavior, may need to add back???
'Try different statement
'Response = dbErrorAdded
'Response = acDataErrContinue
Response = acDataErrAdded
'.ColumnWidths = "0.25 in.;0 in.;1 in."
'.LimitToList = False
' RunCommand acCmdSaveRecord
'.ColumnWidths = "0 in.;0 in.;1 in."
'.LimitToList = True
those code commented out are not needed.
when you set Response=acDataErrAdded, the combo will retain the New Category. Again, you are in Validation event, so you don't requery your combo.