I used to have account1 as a Workflow Proxy Account and I have around 400 Project instance with 3 different EPTs on my server, I changed it to account2, both accounts has all the Global Permissions and Category Permissions Checked.
Now whenever the WF of any instance moves a step forward, I get Queue Errors:
WorkflowCannotChangeWorkflow, ReadProjectEntities: GeneralSecurityAccessDenied.
When I go to Settings -> Enterprise Project Types I find my 3 EPTs
When I go to Settings -> Change or Restart Workflows I find a fourth EPT called "None" that contains all the projects that were affected by WorkflowCannotChangeWorkflow error!!
How to change Workflow Proxy User Account (while having instances with the old account)?