Im trying to create a form that has pre filled date fields. I tried using ISO 8061 date formats that get pre filled correctly and show the date picker correctly. But when I do not make any changes (do not pick any other date via date picker) and leave in the pre filled date while submitting, I get an error. Looking at the logs the ISO 8061 default value that I put in as the default value does not get correctly converted into long value. This works correctly if I choose any other date via the date picker.
Ok, from the log file it is pretty apparent that this issue is not at all Alfresco-related. You are working with the Collibra Data Governance Center, which internally uses the Activiti engine. We could move this question into the space for Activiti-related topics (Alfresco Process Services & Activiti (BPM)), but the value conversion is being done by a Collibra-specific component (CustomDateTimeFormType) and thus you should file your question with that commercial vendor instead of this community platform, which does not deal with the specific product.