Front End update fails with error 502 only if I click 'Update All'. Succeed if 'Update' individially

[Bathinda (Bathinda Helper)]

I’ve two container setup, with outer Nginx Reverse Proxy.
Since yesterday, if I try to ‘Update All’ from front end admin panel, it fails with this error:

But if I click the first/individual ‘Update’ button (under ‘Status’ column) in the very first row ‘Discourse. New Version available’, then it succeeded.

======================= I’ve tried twice after rebuilding from back end since yesterday. Git pull is also ok.
My website!

[NateDhaliwal]

Are there any errors in /logs or in the browser console?

[Bathinda (Bathinda Helper)]

I’m sorry that I’m not any expert in logs or sidekiq reading. But I can do in backend/terminal.
Logs ARE showing some errors though:

Sidekiq earlier: