“We’re sorry, but something went wrong. Error ID # [00000000-0000-0000-0000-000000000000]. We’ve been notified about this issue and we’ll take a look at it shortly. Thank you for your patience.”
Unfortunately, the error message doesn’t give us any clue of the root cause as there is no error log you can download.
Here is the trick: Disable the Custom Error Screen which gives you more details about the error, including stack trace and exception message. Note: This function works only on Dynamics 365 Portals (v8.4) or above.
STEP 1: GO TO OFFICE 365 ADMIN CENTRE IN DYNAMICS 365 (YOU MUST HAVE THE O365 ADMINISTRATOR ROLE)
STEP 2: FIND APPLICATION > PORTAL > MANAGE
STEP 3: PORTAL ACTION > DISABLE CUSTOM ERRORS
NOW YOU CAN SEE THE DETAILS OF THE ERROR LIKE THIS:
This message explains that I have duplicate fields in one form. In CRM, the same field can be placed in multiple places. But in a Dynamics 365 Portal form, all fields must be unique.