Software upgrade procedures?

There is a lot of information on validation of software de novo, but references to software upgrades are usually only ~ ‘check that the system performs the same before & after upgrades’. Can anyone refer me to more specific instructions or a list of recommended procedures & documentation? thanks

You know, that’s pretty much it. The first thing to remember is that you have an existing suite of documentation and testing through the SDLC for the original software. For the upgrade, you compare to changes the manufacturer identified, possibly in the release notes, to your documentation and testing (gap analysis). Then you make the appropriate modifications to the documentation and re-execute the tests. This method is applicable to modification made for patches and for upgrades.
There are issues regarding the extent of modification that you need to take into account. For patches, the modification are usually limited and targeted, so the gap analysis is not overly complicated, relative to the sytem, and the existing test plans can usually be used with some modification. For upgrades, that may or may not be the case. I’ve seem upgrades in which the entire front end was redesigned, which had a huge impact on the existing test plans. The strategy and methodology remained the same, but the entire suite of tests had to be re-written.
Also be aware of the “new” functionality that sometimes comes along with upgrades. These threads will need to be weaved through your entire suite of SDLC documentation.
Hope this helps. If you would like more targeted feedback, please provide a little more detail with respect to the system size and complexity and possibly the extent of the upgrade.

I would use the following point to focus my validation effort:‎
‎1. Verify new functionality is available and that it works. ‎
‎2. Verify that all critical functions/ GxP are subject to regression ‎testing
‎3. Backup the system prior to the upgrade to insure rollback can be ‎easily achieved.‎
‎4. ‎Representative testing for non-GxP-critical areas of the system functionality that have not ‎changed since original validation.

Hope you will find it useful. ‎