Breakpoints stopped triggering in MonoDevelop 4.0.1

Been using Unity for a while now, and with the latest update we also received a new version for MonoDevelop. Breakpointing before 4.0.1 has been a charm, and attaching debugger hasn’t been a problem. Now, however, it seems like I cannot trigger a breakpoint consistently. Sometimes it works, sometimes it does not. It’s rather random in this regard, and I’m having trouble finding a correlation for the bug.
I’ve tried to reinstall Unity and MonoDevelop to no avail. I’ve also repeatedly cleaned/rebuilt the solution, also to no avail.
Does anyone else have these issues?
I’m using Windows 7.

I solved it.

It appears that when this breakpoint-error occurs I have to go into monodevelop, alter a random file, focus unity, let it compile, go back into monodevelop and revert it (ctrl-z), save, focus unity, let it compile, and then attach a debugger.
Let me know if you find a better solution.

When this happens to me, there is usually first a modal pop-up in Unity, talking about some issue with doing something with a file. If I press cancel in this pop-up, the debugging stops working normally. I noticed that if during this pop-up I focus on Monodevelop and close it (save files first!), focus on Unity, press Re-Try in the pop-up, and then re-open Monodevelop, I can debug normally again (attach to process first, of course).

Just wanted to share this tip.

thats the craziest thing i have ever heard this is clearly a broken feature why do they not just fix it? this is a necessary feature in monodevelop it breaks other features of the source code debugging as well.

Yep that works for me too. When I just typed loads of spaces into another file it popped up with a dialog top right asking me to convert all the line endings which I did. Perhaps this is main problem. Anyway - that solution works.

  1. In mono-develop open a file other than the one you are trying to set a breakpoint it, and type in some spaces somewhere (so you don’t need to undo).
  2. Save → If the convert line endings dialog comes up ->Select convert all files.
  3. Jump back to Unity and the little spinner down bottom right goes aroundshowing the files are being compiled.
  4. Back in MonoDevelop hit the Play button to Attach to the unity process and the break points work.