diff --git a/packages/frontend/src/os.ts b/packages/frontend/src/os.ts
index e95aa90254..5e05e73884 100644
--- a/packages/frontend/src/os.ts
+++ b/packages/frontend/src/os.ts
@@ -73,10 +73,6 @@ export const apiWithDialog = (<E extends keyof Misskey.Endpoints, P extends Miss
 		} else if (err.code === 'ROLE_PERMISSION_DENIED') {
 			title = i18n.ts.permissionDeniedError;
 			text = i18n.ts.permissionDeniedErrorDescription;
-		// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
-		} else if (customErrors && customErrors[err.code] != null) {
-			title = customErrors[err.code].title;
-			text = customErrors[err.code].text;
 		} else if (err.code.startsWith('TOO_MANY')) {
 			title = i18n.ts.youCannotCreateAnymore;
 			text = `${i18n.ts.error}: ${err.id}`;