Hello @Deepakpais!
Sorry to hear you have got into trouble with Flame 2026. As we all know, the default locations for the project data and cache are now defaulting on the system drive since you are now free to define this location at your will. System drive is a starting point and one might prefer to set the Cache location to an external drive since cache to avoid such issue. In you case, you have probably rendered an effect and filled the drive, causing the metadata of the project to not be correctly saved, thus the error message you got when restarting Flame.
The process of restoring backups has not changed much with Flame 2026 and this article is still valid, minus the new Flame 2026 locations and file types:
The back-up files are located in /catalog_AUTO_BACKUP/.
The content of these backups can be unarchived using the tar -xvf and then you can replace the corrupted files with the restored file as the article states. We will provide in a near future an updated documentation for this updated workflow.
if all this is too complicated, I would recommend to just delete the project and create a new one and define another Media Cache location and you should be good to go.