Repair Attempt Failure

I tried running a repair of v9.1.2109 because I can no longer delete junk mail from either of my mail accounts but the repair process failed and I receive this error code on every repair attempt:

The file ‘fil00314F58AEBE3706A06CE9222F5EC628’
cannot be installed because the file cannot be
found in cabinet file ‘MailClient.cab’. This could
indicate a network error, an error reading from the
CD-ROM, or a problem with this package.

I am having a similar problem, using the same (latest) .msi install file to initiate a repair (because my backup process is suddenly unfeasibly long. In my case it’s:

The file ‘filQos7ydFFB945sPgYIxk5RSnITcM’ cannot be installed because the file cannot be
found in cabinet file ‘MailClient.cab’. This could indicate a network error, an error reading from the CD-ROM, or a problem with this package.

This is an error with the Windows Installer Service. Typically it happens when you have used some “cleaner utility” to tidy up your disk or registry, and it has deleted cached files that the WIndows Installer Service needs.

However, repairing the eM Client installation won’t have any effect on the backup. If the backup zip file is very large, it is because the database is very large. You can delete some messages, especially those with large attachments, then empty the trash. The the database size will decrease, and so the backup zip file will be smaller.