6 Answers, 1 is accepted
Please, excuse us for the inconvenience.
Yes, you are right. We have introduced a breaking change in out services. To work around it, you have to remove the old version of Progress Control Panel and install the latest one. I have attached the latest version for your convenience. You can also download it from your account page.
Regards,
Vesko
Progress Telerik

I'm getting the same error.
Thanks,
Brian
We are sorry for not getting right from the first time. We have deprecated the old version of the Control Panel now. So, if you start it, you will receive the "Old Progress Control Panel Version" message dialog with a download button. Use that button to get the latest version and remove the old one.
Please have in mind that you have to remove the old version from your system manually (from Control Panel\Programs\Programs and Features). Otherwise, the old version will be launched no matter what .exe is used (even the latest one).
Regards,
Vesko
Progress Telerik

So, just to be clear... There are two different Brian's in this conversation. :)
Let me start with the fact that I like to keep my stuff updated for security reasons, so I love your control panel because it gives a central place to maintain your packages. I am much less likely to support a purchasing a software development package from a vendor that does not have something similar (I am looking at you Redgate >:( ).
So on to the issue at hand. For some reason, I got an email alert with your first reply, but it never showed on the site (clicking the link brought up a 404), which means that your attachment was never available. However, I did go and download the updated software and ran into the you mention issue because I did not uninstall first. I was able to get everything figured out.
Normally, your control panel updates itself, so this could be a pretty big disruption for some people since there was no communication about it (at least none that I saw). There ought to be a way to code it so that the old one could update itself into the new one (maybe tweak the services name in the new one?). Barring that, it would help if you (Progress) would send an email to the user base ahead of time so that they are aware and to inform them of the process for installing the new software. This would help keep people from wasting time (a.k.a. money in my business) searching for a solution on the web and wondering if the problem was on their side.

Thank you very much for your suggestion regarding the Progress Control Panel. We completely understand your point and we will take it in consideration. The issue with the missing forum thread is under investigations now. After all, we are happy to hear that you find out how to upgrade the Control Panel.
The request to enable end users to edit their forum posts has been re-evaluated numerous times. You can find our statement about it here.
Regards,
Vesko
Progress Telerik