In either case do as instructed and once you have completed this step the GUI will now display the backup task with a Back up now button appearing. Click on the Reconfigure button and you will be prompted to either re-select the backup files location or, you may be prompted to re-selected the source data. You will see that the task will display a button now that says Reconfigure rather than Back up now. This will import the task back into the GUI. Once the backup files are showing click to select the first file in the list and click on the Add button. This will open an explorer style window, navigate to the backup file location where the task in question here stored its backup files. To the right of that is another carat (v), click it and select Add existing backup. To do that look to the bottom of the task list column to where the Add backup appears. Once that task is removed you will need to add it back in the list. Next click on Remove to remove the task from the backup list in the GUI. To remove the task and retain the remaining backup files, click on the carat (v) to the right of the task name in the backup list and from the menu that appears select Delete. My suggestion is to Remove the backup task for these backup files from the application GUI then, add the backup files back into the application GUI, reconfigure the task (only a minimal amount of configuration required), and then run the task to get things back on track. In all likelihood, it is the database which has issue and not the backups themselves.

Gmod file is corrupt