Ok I thought I’d post on this because it stumped me for close to 2 hours. So in my scenario, I have a WSS 3.0 installation with several SharePoint Designer workflows built. Many of these workflows use the Useful SharePoint Designer Custom Workflow Activities solution available on codeplex. After doing a migration from one server to another, I found that when I attempted to open up my workflows that contained those custom activities, I would get an error:
Failed to load workflow.
Really frustrating error because it gives you absolutely nothing to go on. I do want to mention that I also tried building a brand new workflow and selecting one of these custom workflow activities and the behavior was odd. If i tried to add one as an ACTION inside my workflow designer, nothing would happen. No error, but the activity wasn’t added to the step either. It was as if my click/selection had no effect.
So I made the decision to completely remove and reinstall the custom activities. The codeplex solution comes nicely packaged using the SharePoint Installer, so all I had to do was run a remove and then a reinstall. Normally, a final step to getting this working according to the InstallGuide.txt is to:
Go to Central Administration -> Application Management -> Manage Web Application Features and activate the feature for desired web applications (usually it’s Sharepoint – 80 or Sharepoint – 443).
The odd thing was that I found this step was already done for me and the solution was listed as already deployed. So back to SharePoint Designer I went, double clicked on the .xoml file, damn, same error! I found several blog posts indicating that I should clear the SharePoint Designer cache. So I closed down SD, deleted the folders starting with 12.x.x.x and loaded SD back up. I tried to open my xoml file, still no luck, same error.
At this point I was getting pretty confused. I manually did a check of the Assembly to make sure it contained the DP.SharePoint.Workflow dll, I double checked the Features folder to make sure it contained the DP.SharePoint.Workflow folder and I make sure the .ACTIONS file was contained within the Workflow folder and that the permissions on it were not wonky. I also verified the web.config contained the safe control entries for that dll. All looked good to me.
FINALLY, I decided to compare my web.config against the old server’s web.config to make sure that I wasn’t missing anything. I did a quick search on DP and found that the old web.config contained one more entry than my new web.config did:
<authorizedType Assembly="DP.Sharepoint.Workflow, Version=220.127.116.11, Culture=neutral, PublicKeyToken=0298457208daed83" Namespace="DP.Sharepoint.Workflow" TypeName="*" Authorized="True" />
So it would appear that I was missing this authorized type necessary for custom workflow activities. How or why this did not get added when I did my reinstall, I have no idea. But once that entry was added back, I was good to go again. My workflows open just fine without error.
I hope this helps someone else out there!