How do I identify and recover Redis when ZCenter login or resource synchronization fails?

Issue/Introduction

This article describes how to troubleshoot login authentication, permission retrieval, and resource synchronization issues caused by an unreachable Redis instance, authentication failure, connection timeout, or Redis service failure. Different services might return different results for Redis errors. Use connection tests and service logs to determine the cause.

Symptoms

• Login, token refresh, or access to an authenticated API fails, possibly with HTTP 401. The log might contain Token expired, Token validation failed, Token verification failed, or Auth error.
• Cloud environment resource synchronization does not run, a synchronization task keeps retrying, or synchronization of a single resource times out. The log might contain resource sync get lock timeout! or Failed to acquire lock during resource sync.
• Role permissions cannot be retrieved correctly, the page reports insufficient permission, or login-lockout behavior is abnormal.
• Service startup or runtime logs contain client errors such as Redis connection refused, timeout, or authentication failure. Use the actual client logs for the exact error text.

Environment

• Product: ZCenter
• Version: 5.1.0
• Component: Base, Gateway, and resource synchronization services that use Redis/Redisson
• Deployment: Single-node or multi-service deployment. Use the Redis address and password from the actual runtime configuration.

Possible causes