Citrix recently released the eagerly anticipated HRP02 for XenApp 6.5, which contains around 87 hotfixes bundled into this one rollup. You can download it here.
While installing this patch onto several servers in a farm, most of them worked fine however on one server the patch installation hung part way through (at around 90%) with no apparent errors or issues recorded in the event log.
Restarting the server and retrying the install with AV disabled, Citrix services stopped, third party services stopped had no effect. Next step was to enable logging by installing the patch using the following command line:
C:\Temp> msiexec /p XA650W2K8R2X64R02.msp /L*V c:\temp\hrp02.log
Examining the resulting log file revealed the issue – this particular server had the XenApp install run from a UNC network share that no longer existed, and could not locate the original install media:
A quick registry search revealed this original UNC path of the install media was set in multiple places in the registry, for each of the individual components that make up a XenApp install (eg base XenApp install, Flash extensions, Delivery Services console etc all have individual installers). After a bit of find and replace work, and a restart of the server, the patch install completed successfully!