Another stupid way to waste an hour or two.....

When developing SharePoint add-in try to remember if you put a previous version of the DLL in the GAC or not. I have just wasted a couple of hours trying to work out why a new version of a DLL is not being read from a site collection's bin directory, when there was an old version in the GAC.

Of course this would not have been an issue if I had been checking the version number properly! A good argument for pair programming to avoid these stupid blind spots