I upgraded to the latest release to find out it would not work on my limited system. Then uninstalled after backing up my info. Reinstalled the release that worked, edited the web.config files...Nothing.
Finally I had to do a System restore, thank Microsoft that it restored the web.config file. backed the directory up. uninstalled everything. rebooted, installed the last working release. and went through the web.config file only coping the security strings that did not match.
This worked, the only caveat is all unattended machines had to be rebooted to show on my side.

Lesson being, Save now Save Often. Gamer 101...

every time I perform an upgrade I make a copy of the entire screenconnect folder. This can be done live so it is very easy and very small. This gives you everything you need if there was ever a problem.