Knowledge

ERROR_SXS_ASSEMBLY_NOT_FOUND - 14003 (0x36B3)

The referenced assembly is not installed on your system.

Updated: Feb 21, 2026

Technical Background

The ERROR_SXS_ASSEMBLY_NOT_FOUND error code is a specific error that occurs within the Windows Side-by-Side (SXS) assembly management system. The SXS subsystem manages assemblies and their dependencies in a way that allows multiple versions of an assembly to coexist on the same machine without conflicts.

Error Details

The ERROR_SXS_ASSEMBLY_NOT_FOUND error indicates that the system attempted to load or reference an assembly, but the required assembly was not found. This can occur due to various reasons such as incorrect installation, missing dependencies, or issues with the SXS manifest files.

Common Causes

  • Incorrect Assembly Name or Version: The name or version of the assembly specified in the application or configuration file does not match any installed assemblies.
  • Missing Dependencies: The referenced assembly depends on other assemblies that are not present on the system.
  • Corrupted Manifest Files: Issues with SXS manifest files can lead to incorrect references and result in this error.

Real-World Context

This error typically occurs when an application or service attempts to load a specific version of a .NET assembly, COM+ component, or other managed code assemblies. It is common in environments where multiple versions of the same assembly are installed, but the correct version is not available at runtime.

Is This Error Critical?

The criticality of this error depends on the application or service that encountered it. If a critical system service fails due to this error, it can lead to system instability or downtime. However, for non-critical applications, this might only result in a user experience issue where the application does not function as expected.

How to Diagnose

  1. Review Operation Context: Determine which assembly was being referenced and ensure that the correct version is required by the application.
  2. Validate Parameters: Check if any parameters passed to the operation are incorrect or missing, such as the path to the assembly file.
  3. Confirm Object Types: Ensure that the object types expected by the SXS subsystem match those actually present on the system.
  4. Verify Input Data: Confirm that all necessary dependencies and manifest files are correctly installed and not corrupted.
  5. Check Limits or Constraints: Verify that there are no resource limits or capacity issues preventing the assembly from being loaded.

How to Resolve

  1. Correct Parameter Usage: Ensure that the correct version of the assembly is specified in the application configuration or code.
  2. Adjust Operation Context: Modify the operation context if necessary, such as specifying a different path to the required assembly file.
  3. Restore Data: If manifest files are corrupted, restore them from backup or reinstall the relevant components.
  4. Retry Operation with Valid Inputs: Attempt to load the assembly again after ensuring all prerequisites are met.

Developer Notes

  • Always ensure that your application is correctly referencing the required assemblies and their versions.
  • Use tools like sfc /scannow to check for corrupted system files, including SXS manifest files.
  • Consider using deployment tools or scripts to manage assembly dependencies effectively.

Related Errors

  • ERROR_SXS_FILE_HASH_MISMATCH: Occurs when the hash of an assembly does not match the expected value in the manifest file.
  • ERROR_SXS_MANIFEST_IDENTITY_NOT_TRUSTED: Indicates that a manifest identity is not trusted by the system.
  • ERROR_SXS_KEY_CONTAINER_MISSING: Happens when a key container required for signing or verification is missing.

FAQ

Q: What does ERROR_SXS_ASSEMBLY_NOT_FOUND mean?

A: It means that the specified assembly could not be found on the system, possibly due to incorrect installation or missing dependencies.

Q: How can I prevent this error from occurring?

A: Ensure all required assemblies and their dependencies are correctly installed and up-to-date. Use tools like sfc /scannow to verify file integrity.

Q: Can this error be caused by corrupted data?

A: Yes, issues with SXS manifest files or corrupted assembly files can lead to this error.

Summary

The ERROR_SXS_ASSEMBLY_NOT_FOUND error indicates that a required assembly could not be found on the system. This error is specific and typically occurs in environments where multiple versions of assemblies are managed by the SXS subsystem. By understanding the common causes, diagnosing the issue, and taking appropriate steps to resolve it, developers can ensure smooth operation of their applications and services.