My site is completely unreachable
A completely silent site is paradoxically easier to diagnose than a half-broken one: only a few links sit between a visitor’s browser and your files, and each leaves a different trace when it fails. Before calling anyone, these four checks tell you who to talk to.
Read the message on screen, it is never generic
Browsers rarely say "the site is broken". They show a precise sentence, and that sentence names the link that failed. "DNS server not found" or "address not found": the domain name no longer resolves to a machine address, so the problem sits with the registrar or in the DNS zone, not in the site. "Connection refused" or "timed out": the name resolves fine, but the machine is not answering — server stopped, firewall, or suspended hosting.
Conversely, a 500 error, a 503 error or a blank page mean the server did answer. The network works, the hosting works: it is the programme that stopped. That is an entirely different conversation.
Four checks before anything else
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Check it is not just you
Test from a mobile connection, with no office wifi and no VPN. An office firewall or an IP address blocked by the server produce exactly the same screen as a global outage.
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Check the domain name
An expired domain cuts the site off overnight, with no visible warning on the site itself. Log in to your registrar and look at the expiry date and status.
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Check the hosting account status
Unpaid invoice, quota exceeded, suspension for abuse: the host sends an email, often to an address nobody reads any more. The control panel shows the real state.
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See whether the server answers at all
If the admin area or a host status page answers while the public site does not, the failure is in the application: configuration, database, or a corrupted configuration file.
What I look at next
When the server answers but the site does not appear, the rest happens in the logs. The web server error log holds the exact moment and the file involved; the CMS log holds the application message. In the vast majority of cases, the useful line is the first one to appear at the moment of the switch, not the most repeated one.
- A full disk stops the server writing its temporary files: the site halts although nothing was changed.
- A PHP version change decided by the host makes an old module incompatible, and the site falls over at the next restart.
- An expired certificate does not stop the site, but the browser blocks access before displaying it, which feels identical.
Carry on with the right page
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Emergency work
What I do in the first hours when a shop is down.
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500 error on PrestaShop
When the server answers but the site returns an error, on PrestaShop.
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Critical error on WordPress
The same symptom on WordPress and WooCommerce, with its own causes.
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DNS explained
Why a domain can stop leading to the right server.
Describe your need in one minute
A few targeted questions so I can reply with an estimate rather than another questionnaire.