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Type.GetType throws exception for all invalid element types

  • Article

Type.GetType(String) now throws a TypeLoadException for all types with an invalid element type, including byref-of-byref. Previously, this method returned null for some corner cases.

Previous behavior

Type.GetType(String) threw a TypeLoadException for most types with an invalid element type, except a few corner cases such as byref-of-byref. For example, the following code returned null in .NET 7:

Type.GetType("System.Object&&")

New behavior

Type.GetType(String) throws a TypeLoadException for all types with an invalid element type, including byref-of-byref. For example, the following code (which returned null in .NET 7) throws an exception in .NET 8:

Type.GetType("System.Object&&")

Version introduced

.NET 8

Type of breaking change

This change is a behavioral change.

Reason for change

.NET had multiple type-name parsers, and it was not unusual for them to have different behavior in corner cases like this one. The behavior was unified on:

  • If the type with the given name is not found, return null.
  • If the type is invalid, throw TypeLoadException. "Invalid" types include types with generic constraint violations or invalid composition of parameter types.

If your code relied on a null return value for these corner cases, change it to catch a TypeLoadException instead.

Affected APIs