LoadFrom Method (String, Byte[], AssemblyHashAlgorithm)

Assembly.LoadFrom Method (String, Byte[], AssemblyHashAlgorithm)

.NET Framework 4.6 and 4.5

Loads an assembly given its file name or path, hash value, and hash algorithm.

Namespace:   System.Reflection
Assembly:  mscorlib (in mscorlib.dll)

public static Assembly LoadFrom(
	string assemblyFile,
	byte[] hashValue,
	AssemblyHashAlgorithm hashAlgorithm


Type: System.String

The name or path of the file that contains the manifest of the assembly.

Type: System.Byte[]

The value of the computed hash code.

Type: System.Configuration.Assemblies.AssemblyHashAlgorithm

The hash algorithm used for hashing files and for generating the strong name.

Return Value

Type: System.Reflection.Assembly

The loaded assembly.

Exception Condition

assemblyFile is null.


assemblyFile is not found, or the module you are trying to load does not specify a file name extension.


A file that was found could not be loaded.


assemblyFile is not a valid assembly; for example, a 32-bit assembly in a 64-bit process. See the exception topic for more information.


assemblyFile was compiled with a later version of the common language runtime than the version that is currently loaded.


A codebase that does not start with "file://" was specified without the required WebPermission.


The assemblyFile parameter is an empty string ("").


The assembly name is longer than MAX_PATH characters.

The assemblyFile parameter must refer to a URI without escape characters. This method supplies escape characters for all invalid characters in the URI.


File transfer protocol (FTP) is not supported. If the URI supplied for assemblyFile is an FTP address, the assembly is not loaded. No exception is thrown.

assemblyFile may be absolute or relative to the current directory, and the assembly is loaded into the domain of the caller.

Assemblies can be loaded into one of three contexts, or can be loaded without context:

  • The load context contains assemblies found by probing: in the global assembly cache, in a host assembly store if the runtime is hosted, or in the ApplicationBase and PrivateBinPath of the application domain. Most overloads of the Load method load assemblies into this context.

  • The load-from context contains assemblies for which the user provided a path that is not included in probing. LoadFrom, CreateInstanceFrom, and ExecuteAssembly are examples of methods that load by path.

  • The reflection-only context contains assemblies loaded with the ReflectionOnlyLoad and ReflectionOnlyLoadFrom methods; code in these contexts cannot be executed.

  • If the user generated or found the assembly, it is not in any context. This applies to assemblies loaded using overloads of the Load method that specify a byte array containing an assembly, and to transient dynamic assemblies created with reflection emit and not saved to disk.

The load-from context allows an assembly to be loaded from a path that is not included in probing, and yet allows dependencies on that path to be found and loaded because the path information is maintained by the context.

The LoadFrom method has the following disadvantages. Consider using Load instead.

  • If an assembly with the same identity is already loaded, LoadFrom returns the loaded assembly even if a different path was specified.

  • If an assembly is loaded with LoadFrom, and later an assembly in the load context attempts to load the same assembly by display name, the load attempt fails. This can occur when an assembly is deserialized.

  • If an assembly is loaded with LoadFrom, and the probing path includes an assembly with the same identity but a different location, an InvalidCastException, MissingMethodException, or other unexpected behavior can occur.

  • LoadFrom demands FileIOPermissionAccess.Read and FileIOPermissionAccess.PathDiscovery, or WebPermission, on the specified path.

  • If a native image exists for assemblyFile, it is not used. The assembly cannot be loaded as domain-neutral.

The assembly is loaded with the evidence that the loader supplies.


to load an assembly with evidence. Associated enumeration: SecurityPermissionFlag.ControlEvidence


for reading a URI that begins with "file://". Associated enumeration: FileIOPermissionAccess.Read


for reading a URI that does not begin with "file://".

.NET Framework
Available since 4.0
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