After you install the following July security updates for SharePoint Server, existing Microsoft SharePoint 2010 workflows stop functioning. When this issue occurs, "c42q8," "c42ra," or "c42rh" event tags are logged in the SharePoint Unified Logging System (ULS) log.
This issue occurs because an additional validation was added in the July security update for SharePoint Server. The validation causes the existing SharePoint 2010 workflows to stop functioning.
To work around this issue, locate the "c42q8," "c42ra," or "c42rh" event tags in the SharePoint ULS log. In these event entries, you can find details about why the workflow is blocked, per these guidelines:
If the blocked parts are "out of the box" workflows or workflow activities, contact Microsoft Support.
Additionally, you can contact the farm administrator to temporarily disable the additional validation by using PowerShell:
In PowerShell, run the following cmdlets:
$farm.EnablePreParseSecurityCheckForWorkflow = $false
If the blocked parts are written by using custom code, and you deploy them yourself in SharePoint Server, you should do a security review on the type that you’re trying to use. If that type is determined to be safe, you can add it to the web.config’s list of authorized types. Otherwise, you should create an alternative implementation that does not violate the security validations.