This is strange because inside the server we have different organizations but only on this client we had the error. We found this solution:
- Go to the Account/Contact form.
- Remove the ParentAccount field which is lookup and causing the issue
- Now publish all the customization refresh it and make sure it is not in the form.
- Next, add it again on the form of account entity and publish all the customizations.
- Check if you still see the issue.
That’s the easy solution. The problem is random and not in all organization we have and it can be on Account or Contact form