I'm receiving this error (see below) in Civil 3D 2019 on one guy's computer here at the office so my custom DLL file won't load (I changed the name of the file to file.dll for AUGI purposes). It loads on everyone else's computer and loaded perfectly on his computer in Civil 3D 2017. This file has always been loaded directly from his C: drive and from the same place where it was located when it worked in 2017. Searches in AUGI came up with a solution to load it from a local drive but clearly that's not the problem. Any idea how to fix this? Other blogs talk about adding the switch to his ACAD.EXE.CONFIG file that would allow files to be loaded from a network but that doesn't seem to be the issue since we're loading it from his C: drive. Could installing 2019 and uninstalling 2017 have messed up his .NET framework or something? That's the only difference with his computer... we uninstalled 2017.

Cannot load assembly. Error details: System.IO.FileLoadException: Could not load file or assembly 'file:///C:\file.dll' or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)
File name: 'file:///C:\file.dll' ---> System.NotSupportedException: An attempt was made to load an assembly from a network location which would have caused the assembly to be sandboxed in previous versions of the .NET Framework. This release of the .NET Framework does not enable CAS policy by default, so this load may be dangerous. If this load is not intended to sandbox the assembly, please enable the loadFromRemoteSources switch.