CRM 2011 - Import Solution getting error Unable to load plug-in assembly

Here's my story: I've imported my CRM 4 solution to CRM 2011. Most things look OK, plug-ins mostly work. This import process was done through the CRM Deployment Manager.

Step 2 I wanted to test building a Solution, adding all my customizatio开发者_StackOverflow社区ns to it, export it, and import it to a second organization on the same server.

Its gotten fairly close (its a HUGE improvement over CRM 4). But its failing when it goes to load my plug-in assembly. The CRM Trace and event log aren't providing me any more help than the solution import log file:

Failure 0x80044191 Unable to load plug-in assembly.

My assembly is deployed to disk so its available. I tried unzipping the solution file, and adding my assembly in the solution hierarchy but that didn't help.

Is it because they're CRM 4 plug-ins? Must they be updated to be imported in CRM 5?

Ended up being I was referencing an assembly not in the GAC of the new server. Wasn't related to solutions per-say and I couldn't register directly with the plugin registration tool either (though that gave me more information). So if you see this I recommend trying to register the assembly using the plugin registration tool to get better information.

You should be able to register your old plugins; upgrading plugins isn't required. Have you tried registering the plugin to database instead of disk? Are you able to register this plugin against your 4.0 environment?

See Upgrade Plug-ins and Custom Workflow Activities to Microsoft Dynamics CRM 2011 for more info about upgrading if you decide to try that.

Actually when you try to import your solution in new organization of MS CRM2011 it is throwing exception because MS CRM4.0 plug-ins are using a library "microsoft.crm.sdk.dll" which does not exist in the GAC. Here is a workaround for the registration of MS CRM4 Plug-ins in MS CRM2011 http://social.microsoft.com/Forums/en/crmdevelopment/thread/d3ce2b89-e8d3-4334-9117-fda2193e03a8

Does your plugin assembly have any dependencies (except the obvious microsoft.crm.*)? If so, try to ILMerge everything into one big DLL and deploy it to the database.