One 421 error blocked a full day of posts: a retry playbook for WhatsApp agent send failures
petrusenko_max · x · 2026-11-04
The author found his WhatsApp agent completely stuck after a single group post returned "error 421": the remaining 3 posts that day never went out, and every later run stayed blocked.
His new failure-handling loop:
- Classify the failure before reacting
- A WhatsApp stanza rejection (e.g. error 421) is not fatal
- A local transient error is not fatal either
- Retry that one item once, 90 seconds later
- If it fails again, skip only that item
- Report the skipped item — never swallow it
- Keep the rest of the day's queue moving
Result: previously one bad send stopped everything; now one bad send costs only one post.
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