Attempting to run a .NET DLL built using the Sage CRM .NET API and .NET 4.5 may result in an error being thrown in Sage CRM.
The following error will be displayed:
File not found: C:\Program Files (x86)\Sage\CRM\CRM\CustomDotNet\MyDLL.dll
An error has occurred in a CRM .net customisation. Please contact your vendor to resolve.
DLLs built for .NET 2.0 will run as normal.
The issue is caused by the Sage CRM application pool being set to run under .NET 2.0.
Setting the CRM app pool to run as .NET 4.0 will resolve the issue.
This setting is available under the Application Pools menu option in inetmgr.
While not specifically tested and supported, .NET customisations for Sage CRM will continue to work correctly if built for .NET 4.5.