FileIOPermission failed for assembly with FullTrust Permission Set

8 May 2009 · .net Framework

This post is from 2009 and kept as an archive. What it describes may have changed since.

After setting fulltrust for an .net assembly to enable it to run from a network share I ran into a figured got into an exception saying:

Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed. Source: mscorlib StackTrace: at System.Security.CodeAccessSecurityEngine.Check(Object demand, StackCrawlMark& stackMark, Boolean isPermSet) at System.Security.CodeAccessPermission.Demand() at System.IO.DirectoryInfo..ctor(String path)

After trying a while I figured out, that this occures if the code group points to a single assembly. As soon as I pointed it to the whole directory it worked.
This might be because other assemblies are used by the main application.

The call I used to set the code group is
caspol.exe -machine -addgroup LocalIntranet_Zone -url "z:\pathtofile\*" FullTrust -name "mynewcodegroup"