Intermittent random 401s

[Liam-Shopify]

Hi @Rokas_Va

This sounds similar to this recent issue that was caused by an “nbf” claim timestamp check failing:

401 Unauthorized after app installation - Sessions not being created in production (React Router v7)

Thank you a lot for the response! After creating this post, I was shown a related post that I hadn’t found before. In that post, the user mentioned enabling the ShopifyApp logger in shopify.server.ts, which revealed a "nbf" claim timestamp check failed error — exactly the same issue I encountered. It turned out my server time was about one minute behind. After configuring the firewall to allow outgoing UDP traffic on port 123 (used by NTP) and some ssh/cli magic, the issue was resolved. xxx:~…

If your server’s clock is off by even 1-2 minutes, token validation will fail randomly.