This BizTalk Health Monitor (BHM) load error related to MYHCQueries_MBVQueries.dll—and sometimes MaintenanceRep.dll—is a well‑known and common issue. It typically appears after installing or upgrading BizTalk Health Monitor.
The problem affects all supported BizTalk versions, including BizTalk Server 2016, 2013 R2, 2013, and 2010, and occurs across multiple operating systems, including Windows 10, Windows Server 2016, 2012 R2, and 2012:
Could not load assembly file ‘file:///C:\Program files (x86)\BizTalkHealthMonitor\MYHCQueries_MBVQueries.dll’ or one of its dependencies. Operation is not supported. (Exception from HRESULT: 0x80131515)
📝 One-Minute Brief
A common BizTalk Health Monitor (BHM) error occurs after installation or upgrade when Windows blocks downloaded repository assemblies, preventing BHM from loading MYHCQueries_MBVQueries.dll and MaintenanceRep.dll. The issue is resolved by unblocking the affected files in the BHM installation directory.
CAUSE
That is one of those times that the BizTalk Server team did a great job. Not only throw the error, but they also explain the problem and the solution to solve it.
This error when BHM tries to load the repository files downloaded from the Microsoft Download Center (DLC). BHM is using two repositories for this configuration; the repository files (MYHCQueries_MBVQueries.dll and MaintenanceRep.dll) can be blocked by the OS when downloading from DLC, which may cause this issue.
Solution
Again, the solution to this problem is also explained in the error window:
- Close BHM.
- Go to the BHM installation folder.
- The default path is C:\Program Files (x86)\BizTalkHealthMonitor.
- Right-click in MYHCQueries_MBVQueries.dll and select the Properties option.
- You may see that the security warning at the bottom of the window says: The file came from another computer and might be blocked to help protect this computer.
- Select the Unblock option, then click OK.
- Do the same steps for MaintenanceRep.dll.
Once you have unblocked both files, you should no longer see the security warning when you go back into their properties, and if you try to execute BHM again, all the above-mentioned errors related to loading repositories should be resolved.
Note: If you have not yet installed BHM, you can also follow the above steps on the unzipped package prior to installing BHM.
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