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System.Drawing OutOfMemoryException changed to ExternalException

GDI+ error handling in System.Drawing has been updated to throw ExternalException instead of OutOfMemoryException for Status.OutOfMemory errors.

Version introduced

.NET 10 Preview 5

Previous behavior

When GDI+ encountered Status.OutOfMemory errors (often due to invalid input rather than actual memory issues), System.Drawing APIs threw OutOfMemoryException.

New behavior

Starting in .NET 10, when GDI+ encounters Status.OutOfMemory errors, System.Drawing APIs now throw ExternalException.

Type of breaking change

This is a behavioral change.

Reason for change

GDI+ isn't particularly good at returning errors when it's unable to create internal objects. There are many cases where object creation fails due to invalid input, and higher-level code gets a null and turns it into Status.OutOfMemory. This is frequently a source of confusion since the error is often not related to actual memory issues.

The change to ExternalException provides more accurate error reporting, as this exception type is already thrown in other System.Drawing code paths for similar GDI+ errors.

If your code catches OutOfMemoryException when using System.Drawing APIs, ensure you also catch ExternalException to handle these GDI+ errors.

try
{
    // System.Drawing operations
}
catch (ExternalException ex)
{
    // Handle GDI+ errors (including former OutOfMemoryException cases)
}
catch (OutOfMemoryException ex)
{
    // Handle actual memory issues
}

Try
    ' System.Drawing operations
Catch ex As ExternalException
    ' Handle GDI+ errors (including former OutOfMemoryException cases)
Catch ex As OutOfMemoryException
    ' Handle actual memory issues
End Try

Affected APIs

All System.Drawing APIs that interact with GDI+ and previously could throw OutOfMemoryException for Status.OutOfMemory errors, including but not limited to: