Getting erroring could not load type 'DLL' from assembly after proactive quality update is applied

After the recent Proactive Quality Update, we are encountering the following error:

"Could not load type 'DLL' from assembly."

It appears that the update has impacted the assembly references. Our custom functionality, which calls the C# assembly DLL, was working fine before the update but stopped working after it was applied.

We are currently stuck and need assistance. Could you please help us understand why this issue is occurring and how we can resolve it?

Regards,

Raziq

Categories:

Dynamics 365 Finance

This issue typically occurs due to breaking changes in the Proactive Quality Update, which may have impacted assembly bindings or dependencies in your custom code.

1. Check Event Logs & Plugin Trace Logs

Go to Power Platform Admin Center → Environments → Settings → Plug-in Trace Logs to see detailed error messages.
If this is a server-side issue, check the Windows Event Viewer for additional details.

2. Verify Assembly Version & Binding Issues

The Proactive Quality Update may have introduced new versions of dependent assemblies.
Confirm that your custom DLL is compatible with the latest Dynamics 365 libraries.

3. Update Assembly References in the Plugin / Workflow

Open your C# project and check the referenced Microsoft.Xrm.Sdk and related assemblies.
Ensure you are using the latest versions compatible with the update.
If using early-bound classes, regenerate them using the CrmSvcUtil tool.

4. Recompile and Redeploy the DLL

Rebuild your solution with the correct references.
Deploy the new version to Dynamics 365 using Plugin Registration Tool.

5. Check Strong Naming & Signing Issues

If the update changed assembly signing requirements, ensure your DLL is properly signed and registered.

6. Use Assembly Binding Redirects (If Needed)

If your plugin references an older assembly, you may need to add a binding redirect in the application’s config file.

7. Verify Security & Trust Levels

If the DLL is deployed as an isolated plugin, ensure it has the correct trust level in Dynamics 365.
Some updates may restrict certain libraries in the sandbox environment.

8. Raise a Microsoft Support Ticket (If Issue Persists)