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~/tools / explain-error-message

Explain an error message

Paste a log line or error message — get its meaning, likely causes, commands to check and steps to fix it.

daniele@mikweb: ~/tools — less explain-error-message.md

Good to know

  • The explanation is written by an AI from an admin's point of view — it can be wrong. Understand commands before running them.
  • Paste the whole line, including the service (e.g. postfix/smtpd, nginx, php-fpm) and the error code.
  • If the error code lexicon knows the code, the matching page is linked.

Privacy

The text you paste is sent to this server. There, e-mail and IP addresses and passwords are replaced by placeholders; then the text goes through an automation flow (n8n, own server) to IONOS's AI service in Germany. The text is not stored. To limit use, a salted hash of your IP address is kept for 24 hours. Please do not paste confidential data.

daniele@mikweb: ~/tools — ls

Tools

SPF checkerCounts the DNS lookups of your SPF record (limit: 10).DNS TTL plannerPlans the TTL reduction and the move time.Cron explainerExplains cron expressions and shows the next runs.DMARC generatorBuilds a valid DMARC record to copy.Mail DNS checkChecks MX, reverse DNS, SPF, DMARC and MTA-STS of a domain.Certificate checkExpiry, chain and names of a TLS certificate.Security headersGrades HSTS, CSP and other security headers.JWT decoderShows header, claims and expiry of a JWT — in your browser only.SAML decoderDecodes SAML responses and spots typical errors.nginx for NextcloudGenerates an nginx config for Nextcloud with PHP-FPM.

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