I had to install the August 2010 CU to fix another issue (which it did actually resolve). Unfortunately, it just broke something else.

Problem:

After installing the August 2010 Cumulative Update for SharePoint 2010, the User Profile service may stop working. You will see the following event in the the Application event log, with Event ID 3:

Source: Forefront Identity Manager
EventID: 3

Microsoft.ResourceManagement.Workflow.Hosting.WorkflowManagerException: Forefront Identity Management Service does not support workflows of type ‘Microsoft.ResourceManagement.Workflow.Activities.SequentialWorkflow, Microsoft.ResourceManagement, Version=4.0.2450.5, Culture=neutral, PublicKeyToken=31bf3856ad364e35’.

Fix:

Delete and re-create the User Profile Service application (!!!)

Further reading:

• Problem after installing August CU for SharePoint 2010
• Event ID 3 is logged in the Application log if you run the User Profile Synchronization service after you install hotfix package 2281364 or 2352342 in SharePoint Server 2010