diff --git a/backend/mpc-system/services/server-party/application/use_cases/participate_keygen.go b/backend/mpc-system/services/server-party/application/use_cases/participate_keygen.go
index ba4a9ec0..78159a67 100644
--- a/backend/mpc-system/services/server-party/application/use_cases/participate_keygen.go
+++ b/backend/mpc-system/services/server-party/application/use_cases/participate_keygen.go
@@ -110,7 +110,8 @@ func (uc *ParticipateKeygenUseCase) Execute(
 		return nil, err
 	}
 
-	if sessionInfo.SessionType != "keygen" {
+	// Accept both "keygen" and "co_managed_keygen" session types
+	if sessionInfo.SessionType != "keygen" && sessionInfo.SessionType != "co_managed_keygen" {
 		return nil, ErrInvalidSession
 	}