Thoughts about setup and deployment issues, WiX, XNA, the .NET Framework and Visual Studio
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Our development team has found a possible root cause and workaround for error code 20 that may appear when trying to download television guide data in Media Center 2005. The guide download error code article I previously published describes error code 20 as a file validation error, possibly caused by a mismatched guide package. Previously, the only recommended workaround was to try downloading guide data again later.
We got a hold of a machine that was displaying error code 20, and the developer debugged and found the failure resulted from a call to a cryptographic API that is used to decode guide data (which is downloaded in an encrypted format). For some reason we don't fully understand yet, this API returns a set of permissions that don't permit the guide data file to be opened correctly.
This workaround that we used to resolve this issue is the following:
Error code 20 is being caused by one of the machine keys in that folder, but it appears to be a different key on each computer that hits this problem.
<update date="6/22/2006"> Updated this workaround so that it only includes deleting Media Center-specific RSA keys. The previous workaround ended up deleting the entire RSA key store, which can impact other products on the system. </update>