This is kind of odd. Typically when we see ahead of cache it would mean that the service pack is higher than what is in the commserve downloaded cache.
Assuming that you tried to update SP4 via the commcell gui by right clicking on the client and installing updates you can try to download sp4 below.
Save this package to a UNC path or local to the server and run it.
If this does not work you can go to the base directory of the server and run removeupdates.exe. This will give you the option to remove all updates or last set. In this situation i would recommend that you remove all updates and reapply SP4 using the download above.
Keep in mind that if you use the removeupdates.exe you will most likely need to do a reboot before reapplying the SP.
Let me know if you this helps.
CommVault Messaging Support