Library reported as inaccessible

Issue
The EM Library console reports the library as inaccessible, and the following error is reported in the event log:

The "\\MYSERVER\SophosEM" library update task has failed. INDEX 0x8000ffff
Could not access the EM library. Either there is no valid library or the path is not accessible. Check that there is a shared directory for the library (by default the directory is "Program Files\Sophos Enterprise Manager\library" and is shared as "SophosEM") and that there is an "/index" subdirectory. INDEX 0x8000ffff
Could not lock and read the EM Library database. MCID 0x8000ffff
The version of the EM Library database could not be read, unexpected version number: 17912. MCID 0x8000ffff

Cause
The library may have been removed by someone in your organization, as EM Library is no longer supported.

What to do

Please see the Upgrade Center for more information about upgrading to a more recent version of Enterprise Console.