SSL5 min read
HTTPS warning after a site move: DNS, certificates and redirects
Find whether DNS, the public certificate or a redirect explains the warning.
Troubleshooting guides
Step-by-step fixes for problems website owners run into often. Each guide explains the cause, shows the fix and links to a tool so you can confirm it worked.
HTTP5 min read
Investigate a 403, 404, 502 or 504 website response
Capture the final URL and response, then investigate the operation that failed.
Technical SEO5 min read
A page is crawlable but not indexed: what to check
Check response directives and discovery, then consult the search engine’s recorded indexing reason.
Email5 min read
Set up email DNS while preserving working mail
Separate receiving records from sending authentication and verify every legitimate sender.
Network5 min read
Why a TCP port checker reports closed or timed out
Trace the connection path without disabling the firewall or treating a TCP result as a UDP test.
Redirects7 min read
Fix ERR_TOO_MANY_REDIRECTS: find and break a redirect loop
The usual causes are a CDN in Flexible SSL mode, a wrong site address in your CMS or two rules that disagree about www.
Email9 min read
Emails going to spam? Check SPF, DKIM and DMARC in this order
Read receiving-server headers, check authentication and alignment, then investigate reputation and recipient signals.
DNS6 min read
DNS change not showing up? How propagation really works
Compare authoritative records and resolver caches to investigate a DNS change that has not appeared.
Server config6 min read
Cron job not running? Seven things to check
Check paths, environment variables, permissions, logging and time zones in a cron job that is not running.
Can't find your problem?
Search the tools instead. Each check explains what it finds and what to do next.