App-V Client Error 29-00000057 Changing Cache Size Policy

If you have a client (4.6 SP1 x86 Windows Desktop for sure, perhaps other installs and other installers) that is currently configured for a cache size policy of a maximum size and attempt to use the Client Management Console to modify the setting to instead use the Minimum Free Space option, when you hit apply you will get an error:

“The Application Virtualization Client could not modify file system cache settings. The parameter is incorrect”

Error code ends in 29-00000057

This appears to me to be a bug in the MMC console (or perhaps sftlist which implements the change request). I have developed a workaround for this issue, documented below. Appropriate cautions about backups etc apply, but hey, in the worst case you uninstall and reinstall the client with the correct policy setting.

First a little info gained from looking into this issue. It seems that the MMC uses sftlist (the client service) to implement the change request. Through testing making the change in the other direction, I have determined that there are two mutually exclusive registry entries that should exist, however the settings seem to also be stored inside the fsd cache file as well. Clearing out the cache file will cause the registry settings to be used when the cache file is recreated.

Here is the WORKAROUND. To change from a fixed maximum size to a minimum free size setting, you would do the following in regedit, after browing to the HKeyLocalMachine\Software\{Wow6423Node\}Microsoft\SoftGrid\4.5\Client\AppFS key:

•Delete the FileSize registry entry
•Add a new MinFreeSpace entry; as a DWORD and set the value to the ammount of needed free space (in MB) that must be present whenever the cache file is to be extended.
•Set the State registry entry to 0 (zero)
then reboot the OS. This will clear out the App-V cache file and set the new policy inside the cache file.

Author: Tim Mangan

Microsoft MVP for App-V Citrix CTP