mysql workbench error opening EER
I was facing the same issue, at last i just close the application and restarted, it resolved the issue.
The other solutions did not work for me, for anyone still looking for a solution I managed to open my model by closing the workbench and double clicking the actual .MWB file in the file explorer.
I hope that helps someone.
For me, was by closing other tabs (maybe the tabs that related to eer digram)