You may open the CrashPlan app and see a message which reads "Routine maintenance - Backup will resume automatically when maintenance completes" instead of showing the current backup status.
This message indicates that your backup archive is undergoing maintenance, an intentional and necessary task for every backup archive.
What does Archive Maintenance do?
Archive maintenance is an automated process which runs on each backup destination every 60 days. Its purpose is to perform routine cleanup and check the validity of your archive contents by checking backup archives for data consistency, removing old versions and deleted files, and more.
While your archive is undergoing maintenance, you will not be able to restore files from either the web or the app-based Restore Files menu. Backup will also stop while maintenance is in progress.
What can I do if my Archive is in Maintenance?
Archive Maintenance is necessary for the long term accessibility and efficiency of your backup archive. Because of this, it is not possible to stop an archive maintenance job once it's been started, meaning that you must wait for it to complete. No actions will interrupt or cancel the archive maintenance process once it has been started.
How long does Archive Maintenance take?
The Home screen of the CrashPlan app will display archive maintenance progress and estimate time to complete, but this will change as the server works through the different phases of archive maintenance. It is not possible to determine precisely how long an archive maintenance job will take, though technical support may be able to tell you the duration of prior maintenance jobs to give you a better idea of what to expect.
For more information, see Archive maintenance in CrashPlan for Small Business.