Could not load file or assembly Operation is not supported. Exception from HRESULT 0x80131515
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Understanding the Error: Could not load file or assembly: Operation is not supported. (Exception from HRESULT: 0x80131515)
When working with .NET applications, you might encounter the error message "Could not load file or assembly: Operation is not supported. (Exception from HRESULT: 0x80131515)." This error can be frustrating, especially if you're unaware of its roots and solutions. This article explores the technical background of this error, its causes, and provides guidance on resolving it.
Technical Explanation
The error's HRESULT code `0x80131515` indicates an issue while attempting to load an assembly in .NET. More specifically, the error may occur when trying to load an assembly that is being blocked by the operating system. This typically happens due to security settings that prevent the execution of potentially unsafe files.
Common Causes
- Blocked Assemblies: The most frequent cause of this error is a security feature in Windows which blocks assemblies downloaded from the internet. This occurs because such files are marked with an "Internet" zone identifier in NTFS file systems.
- Improper Trust Levels: Assemblies may not load if they fail to meet the required trust levels set by execution policies within the .NET environment.
- Corrupted Files: Sometimes, assemblies may become corrupted due to incomplete downloads or file system errors, leading to this error during loading.
- Incompatibility: Occasionally, this error can surface when there's a mismatch or incompatibility between different versions of the assemblies or the runtime environment.
Key Points Summary
| Key Factors | Explanation |
| Blocked Assemblies | Windows blocks assemblies from the internet for security reasons. |
| Trust Levels | Assemblies require the appropriate trust settings to load correctly. |
| Corrupted Files | Corrupted or incomplete assembly files can trigger loading errors. |
| Incompatibility | Mismatched versions between assemblies or runtimes cause issues. |
Solutions and Workarounds
Unblocking Files
The simplest and most direct way to resolve this error, when it’s due to the "blocked" status of a file, is to manually unblock the file:
- Right-click on the affected assembly file in Windows Explorer.
- Select "Properties".
- In the "General" tab, if you see an "Unblock" option at the bottom, check it.
- Click "OK" to close the dialog.
Using PowerShell
If you have multiple files to unblock, using PowerShell can be more efficient:
