last backup was July 7 with 155 GB. I thought it needed more storage space so I bought more, ran the backup calculation and it said everything was ok. Tried to back up and got the above error message again. I've searched your forums and online and cannot find any info on (A2206) error for NOBU. I found one post that suggest that I create a "test" text file on the desktop and see if just that file can be backed up. That also failed. I am trying to back up photos on an external hard drive.
Wait... hold off on uninstalling anything. You can't simply reinstall the Norton Online Backup software after uninstalling it without first Adding a New Computer again and setting everything up. It is absolutely the last action that should be taken.
With that said - that error means there is a problem with the data being transferred and indicate a problematic file in the set. The error correction built in is triggering the alert as a result. If you have not made a lot of customization to the file rules I'd first suggest de-selecting a couple of the largest categories to par the backup size down temporarily and run it again. If it completes without the error, add one of the removed categories back. Keep it up till the error surfaces.
If it pops up immediately a scandisk/chkdsk of the system first and then trying again may help resolve the issue. If no the next course of action would be to purge the data set, NOT UNINSTALL. This will leave settings intact. If it comes to that let us know the results of the suggestions first before you do any removal of content online.