Hello! 

Unusual issue. I suspect the “UNDO” folder doesn’t have appropriate permissions to write the files. Can you send a screenshot of Setup > Project preferences > Folders as below so I can see where the rest of your DATA file are located? 

Hello! 

 

Unusual issue. I suspect the “UNDO” folder doesn’t have appropriate permissions to write the files. Can you send a screenshot of Setup > Project preferences > Folders as below so I can see where the rest of your DATA file are located? 

 

 

I have the same issue and I have the correct path to UNDO C:\Users\pacov\Documents\Zemax\Undo

I have this folder. I don’t find the mistake. Someone can help me?

Can you save a plain text file into the UNDO folder? If that fails then it is a permission problem on that folder. That’s unusual though as /user/Docuemnts should be full  control for that user. Anyway, it will resolve whether permissions are the issue.

Does your company have any specific security settings for standard users? You may have some IT policy in place that is preventing access

I can save a plain text file in UNDO folder. I still have the error.

Hello! 

Thanks for pitching in Mark!

I wonder if this is just a corrupt file or Undo database? I’d try closing Opticstudio and deleting everything within the ”UNDO”  folder. Then see how things work going forward. 

I deleted the files in UNDO and then I could made a change in a file but later I got the same message error “Can’t open file ...”