diff --git a/packages/backend/src/server/FileServerService.ts b/packages/backend/src/server/FileServerService.ts
index 2e3e8df7ea..e5d8f39e5a 100644
--- a/packages/backend/src/server/FileServerService.ts
+++ b/packages/backend/src/server/FileServerService.ts
@@ -354,7 +354,7 @@ export class FileServerService {
 		if (!request.headers['user-agent']) {
 			throw new StatusError('User-Agent is required', 400, 'User-Agent is required');
 		} else if (request.headers['user-agent'].toLowerCase().indexOf('misskey/') !== -1) {
-			throw new StatusError('Refusing to proxy a request from another proxy', 403, 'Proxy is recursive');
+			throw new StatusError(`Refusing to proxy recursive request to ${url} (from user-agent ${request.headers['user-agent']})`, 403, 'Proxy is recursive');
 		}
 
 		// Create temp file