The next step is to verify that each software package will work with the new OS and to plan an upgrade path for those that don’t. Using the list developed earlier, contact the vendor and find out whether the software release in use will work after the upgrade. Vendors often list such information on their web sites.
You may wish to test the reliability of the information yourself or find another customer who has already performed the upgrade. Vendors’ ideas about what it means for a version to work often don’t include the features your site needs or the exact configuration you’re going to use. Doing the tests yourself can be expensive but possibly cheaper than a failed upgrade, and reduces the risk of failure. The point of this is risk management. If only one system is being upgraded and if the application is not critical, personally testing it might be a waste of time. If the upgrade is going to be repeated thousands of times, in an automated fashion and in a way that failure would be highly visible, testing is a requirement.
If the software release being used will work on the new OS release, document where you found this information for future reference. If the software isn’t supported on the new OS, you have several options.