It works for me but my customers say it is down.

Your computer is reaching the new host and theirs is reaching the old one, or the reverse. It is propagation. Keep both hosts live until a propagation checker shows the new address everywhere.

The old host already deleted my account. Can you still fix it?

Usually. If the copy on the new host is complete, the fix is configuration. If files are missing, we look for a backup at the old host, in your email, or in a backup plugin before we tell you what can be rebuilt.

Is this the site-down fix or the move fix?

If the move is done and the site is broken, it is the site-down fix: same day, fixed price. If the move itself is half finished, start the move job and we finish it.

Website down after moving to a new host

A site that worked yesterday and broke the moment the move finished has a short list of possible causes, and most of them are quick to fix once named. Start by finding out which host is actually answering, because half of these problems are the old host and the new one both being half-live.

First, which host is answering?

Look up your domain at a DNS propagation checker and compare the IP address it shows with the new host's IP. If some locations still show the old address, you are mid-propagation and the fix is to wait, or to keep the old host live until it finishes. If everything shows the new address and the site is still broken, the problem is on the new host.

The usual causes, by symptom

"Error establishing a database connection": wp-config still holds the old database name, user, password or host.
Every page except the homepage is a 404: the .htaccess rules or nginx rewrite rules did not come across, or permalinks need to be re-saved.
A white page or a PHP error at the top: the new host runs a newer PHP version than the old one, or a required PHP extension is missing.
The site keeps redirecting to the old address or a staging address: the site URL stored in the database was not updated.
"Your connection is not private": the SSL certificate has not been issued on the new host yet, or it was issued before DNS pointed there and failed.
Images missing but text fine: the uploads folder was not copied, or file permissions are wrong on the new server.

What to check in the first ten minutes

Open the new host's error log; it names the PHP error or the missing file directly.
Compare PHP versions on both hosts and set the new one to match the old one for now.
Confirm the uploads folder size matches on both sides.
Confirm the SSL certificate is issued for both the bare domain and the www version.

Should you move DNS back?

Only if the old host is still fully live and you cannot get the new one working within an hour or two. Moving back and forth restarts propagation each time and makes everything harder to diagnose. If the old host is already cancelled or suspended, the way out is forward, and that is a same-day job for us.

Questions people ask

It works for me but my customers say it is down.: Your computer is reaching the new host and theirs is reaching the old one, or the reverse. It is propagation. Keep both hosts live until a propagation checker shows the new address everywhere.
The old host already deleted my account. Can you still fix it?: Usually. If the copy on the new host is complete, the fix is configuration. If files are missing, we look for a backup at the old host, in your email, or in a backup plugin before we tell you what can be rebuilt.
Is this the site-down fix or the move fix?: If the move is done and the site is broken, it is the site-down fix: same day, fixed price. If the move itself is half finished, start the move job and we finish it.