Assuming you have tried after a windows restart it could be time to import your recent iwzip file of the project.

If you don't have an iwzip you will need to rely on the sometimes usefully backup. Select project, click backup, choose a likely candidate and redo.

I try everything... In final restore the .iwzipfile. Check why is this hapend...

Importing an iwzip will never overwrite an existing project. What proceedure did you follow?

I restore the backup, i'm smart with your app and save every data on server in .iwzipfile. I sugest and other users too...

X5 Croatia, you asked why this error occured, this post indicates possible causes. It has been a problem forever made worse by the inbuilt automatic backup failing to create a full backup.

https://helpcenter.websitex5.com/en/post/194459