diff --git a/packages/server/modules/gatekeeper/errors/billing.ts b/packages/server/modules/gatekeeper/errors/billing.ts
index 0f0a78e03..dc5e5e31a 100644
--- a/packages/server/modules/gatekeeper/errors/billing.ts
+++ b/packages/server/modules/gatekeeper/errors/billing.ts
@@ -71,3 +71,9 @@ export class InvalidBillingIntervalError extends BaseError {
   static code = 'INVALID_BILLING_INTERVAL'
   static statusCode = 400
 }
+
+export class UnsupportedWorkspacePlanError extends BaseError {
+  static defaultMessage = 'Unsupported workspace plan'
+  static code = 'UNSUPPORTED_WORKSPACE_PLAN_ERROR'
+  static statusCode = 400
+}
diff --git a/packages/server/modules/gatekeeper/services/subscriptions/upgradeWorkspaceSubscription.ts b/packages/server/modules/gatekeeper/services/subscriptions/upgradeWorkspaceSubscription.ts
index 5c4956e12..d9a22dc73 100644
--- a/packages/server/modules/gatekeeper/services/subscriptions/upgradeWorkspaceSubscription.ts
+++ b/packages/server/modules/gatekeeper/services/subscriptions/upgradeWorkspaceSubscription.ts
@@ -11,6 +11,7 @@ import {
 import { CountSeatsByTypeInWorkspace } from '@/modules/gatekeeper/domain/operations'
 import {
   InvalidWorkspacePlanUpgradeError,
+  UnsupportedWorkspacePlanError,
   WorkspaceNotPaidPlanError,
   WorkspacePlanMismatchError,
   WorkspacePlanNotFoundError,
@@ -265,7 +266,9 @@ export const upgradeWorkspaceSubscriptionFactoryNew =
 
     if (!workspacePlan) throw new WorkspacePlanNotFoundError()
     if (!isNewPlanType(workspacePlan.name) || !isNewPlanType(targetPlan)) {
-      throw new NotImplementedError()
+      throw new UnsupportedWorkspacePlanError(null, {
+        info: { currentPlan: workspacePlan.name, targetPlan }
+      })
     }
 
     switch (workspacePlan.name) {