Solved! Go to Solution.
I ran into the same problem, and none of the solutions worked for me, at least not on their own. I found one more thing that may have been crucial:
After configuring the project to build on the 3.5 framework, I noticed a build warning in Visual Studios output window: warning : The 'language' attribute in the AddIn element is invalid - The value 'CLR4.5' is invalid according to the project's target framework version - The value should be 'CLR'.
After changing the language attribute in Config.esriaddinx file to CLR, things worked again.
Oh, and one more thing: Initially the breakpoint looks invalid (the breakpoint will not currently be hit). Don't let that fool you, because as soon as the addin is loaded, e.g. by clicking on a button, the breakpoint will be valid.
My other configuration:
I believe, like you said, the solutions work together. I remember changing the version from V2 to V4 worked, but I also had to ensure the CLR value was the correct one (in my case <AddIn language="CLR4.5" ...) and target CPU x86
Berend Veldkamp wrote:...
Oh, and one more thing: Initially the breakpoint looks invalid (the breakpoint will not currently be hit). Don't let that fool you, because as soon as the addin is loaded, e.g. by clicking on a button, the breakpoint will be valid....
This is the clincher for me. I changed the runtime version in arcmap.exe.config as per the "unofficial" solution, and I was still getting the invalid breakpoint message. But just as Berend said, as soon as you start your addin, the breakpoint functions as intended. Thank you for saving me pointless additional troubleshooting!
None of these solutions worked for me this time, although at various times in the past one or the other of these techniques did work. There seem to be about a 100 ways that this thing can get off the track and it seems to do that spontaneously, at any time (but especially when there is a deadline looming) and I have wasted literally DAYS messing with these and other solutions trying to fix this. This sucks!