ORLEANS0026: Invalid invokable base type mapping

Property	Value
Category	Usage
Severity	Error
Code fix	Not available

Cause

An applicable custom InvokableBaseType registration is invalid for the grain method’s return type and selected proxy base. Common causes include conflicting registrations, invalid generic arity or constraints, an inaccessible or sealed request base, a missing supported constructor, or an invalid ReturnValueProxy initializer.

Impact

Orleans cannot reliably select or generate the invokable request type for the RPC method. Proxy and request code generation cannot produce a valid custom calling contract.

How to fix

Locate the registration named by the diagnostic, then:

1. Remove conflicting mappings and avoid replacing built-in proxy defaults through assembly registration.
2. Match open generic return and request types by arity and constraints.
3. Use an accessible, non-static, non-sealed request base with a supported constructor.
4. Correct the ReturnValueProxy initializer name and signature.
5. Validate every proxy base selected by GenerateMethodSerializers.

Suppress the diagnostic

Suppression does not repair the source-generation contract, and the source generator can report the same condition separately. Suppress only for a proven analyzer-only false positive after independently validating generated output.

[*.cs]
dotnet_diagnostic.ORLEANS0026.severity = none

See Customize Orleans code generation.