This is a heads-up for anyone doing development on SSIS.

On my current project where we are implementing a SQL Server Integration Services (SSIS) 2012 solution we recently encountered a situation where we were unable to deploy any of our projects even though we had successfully deployed in the past. Any attempt to use the deployment wizard resulted in this error dialog:

The text of the error (for all you search engine crawlers out there) was:

A .NET Framework error occurred during execution of user-defined routine or aggregate "create_key_information":
System.IO.FileLoadException: Could not load file or assembly 'System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) ---> System.IO.FileLoadException: The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
System.IO.FileLoadException:
System.IO.FileLoadException: 
   at Microsoft.SqlServer.IntegrationServices.Server.Security.CryptoGraphy.CreateSymmetricKey(String algorithm)
   at Microsoft.SqlServer.IntegrationServices.Server.Security.CryptoGraphy.CreateKeyInformation(SqlString algorithmName, SqlBytes& key, SqlBytes& IV)
. (Microsoft SQL Server, Error: 6522)

After some investigation and a bit of back and forth with some very helpful members of the SSIS product team (hey Matt, Wee Hyong) it transpired that this was due to a .Net Framework fix that had been delivered via Windows Update. I took a look at the server update history and indeed there have been some recently applied .Net Framework updates:

This fix had (in the words of Matt Masson) “somehow caused a mismatch on System.Core for SQLCLR” and, as you may know, SQLCLR is used heavily within the SSIS Catalog. The fix was pretty simple – restart SQL Server. This causes the assemblies to be upgraded automatically. If you are using Data Quality Services (DQS) you may have experienced similar problems which are documented at Upgrade SQLCLR Assemblies After .NET Framework Update. I am hoping the SSIS team will follow-up with a more thorough explanation on their blog soon.

You DBAs out there may be questioning why Windows Update is set to automatically apply updates on our production servers. We’re checking that out with our hosting provider right now

You have been warned!

@Jamiet