Aug 282014

Being a .net developer you might have wondered if at all there is a way to tell .net assembly binding and loading mechanism (fusion) to look for your assemblies in your shared assembly folder as well. This will be really helpful if your assembly is used with multiple applications so that if they fail to locate an assembly in the appbase or privatepath’s then they start looking for it in your ‘bin’ folder. This prevents you from frequently installing and uninstalling the assembly to GAC for testing purpose.

This is exactly what DEVPATH environment variable does.

How to set DEVPATH

Following example shows you how to setup just need to set assembly look up path to this variable. For e.g.

set DEVPATH=”c:\sharedassemblies\”

To enable DEVPATH look up you’ll also need to modify machine.config file, in my case its located here: C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config\machine.config


<developmentMode developerInstallation=”true”/>


Verify DEVPATH is used

So next time when application runs and starts looking for your assembly it will for sure look in the above path. If fusion logger is enabled and if you open the log file for your assembly you should see something like this…

LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\myapp.exe.Config
LOG: Using host configuration file:
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Found assembly in DEVOVERRIDE path C:\sharedassemblies\Test.DLL

Recently had a customer who asked this question and this looks like to have helped them so thought of sharing this out with you folks as well.

Watch outs
  1. Please be very aware that you’ve set this feature on. You could end up having erratic behavior if somehow DEVPATH has a path containing unsupported path chars like parentheses or if DEVPATH is set to empty.
  2. Please only use this feature in development environments as this feature by passes all normal assembly lookup features as fusion looks up DEVPATH first if enabled.
  3. Please note fusion will look up DEVPATH as if its an AppBase folder so be aware that it will look up subdirectories as well in this DEVPATH. Also all valid assembly name look ups will be done, for e.g. .dll, .exe etc.

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