The "Let's Encrypt rate limit reached" error means too many certificate requests were made for the same domain in a short period, typically from repeatedly removing and re-adding the domain. Let's Encrypt enforces a limit of 5 duplicate certificates per domain per week, and once hit, certificate issuance for that domain is blocked for 7 days. The fix is to wait out the 7-day window without removing or re-adding the domain, and issuance will resume automatically.