mysql workbench orphaned document changes detected

In my case, the problem was caused by deleting the connection with orphaned document changes.

The solution for  Linux-Mint:

• Locate ~/.mysql/workbench/sql_workspaces/your connection name.autosave directory
• Delete it.

On Windows, the above directory should be located at:

• C:\Users\Administrator\AppData\Roaming\MySQL\Workbench\sql_workspaces\

As simple as that.