PrestaShop error 500 or blank screen: what to do right now

You open your shop on a Monday morning and all you see is "Error 500", or a completely blank page, while the weekend's orders sit waiting. A PrestaShop error 500 or a blank white screen almost never means you've lost your shop: it means something has failed behind the scenes and PrestaShop can't tell you what. First, don't touch anything blindly; then either diagnose it with the steps below or hand the problem to someone who'll be on it in less than 12 hours.

What does error 500 mean in PrestaShop?

It's a generic server message: "something went wrong and I can't finish loading the page". It doesn't say what. The blank screen is the same thing, just without even the message: the shop is set up not to show errors to customers, so it shows nothing at all.

The good news is that your products, customers and orders are still in the database. What's broken is the part that displays them, and that can be fixed.

Why has my shop suddenly gone down?

There's almost always something that changed just before. The most common causes are:

• A new or updated module that clashes with another one or with your version of PrestaShop.
• A PrestaShop or theme update that only got halfway through.
• A change on your hosting: your provider has upgraded the PHP version (the language PrestaShop runs on) and your shop isn't compatible with the new one.
• The cache, the temporary files PrestaShop keeps to run faster, has become outdated or corrupted.
• The server runs out of memory on the heaviest pages, such as the catalog or the back office.
• File permissions set wrong after moving the shop or uploading something via FTP.

Before anything else, think back: what was installed, updated or changed in the last few days? That answer saves half the work.

What do I do right now so I don't make it worse?

1. Don't reinstall PrestaShop or start deleting modules at random. Uninstalling a module can wipe its settings and its data.
2. Ask your hosting provider for a backup of the files and database exactly as they are now, or make one yourself from their control panel. That way any test can be undone.
3. Check whether everything fails or just one part. Is it the home page, only the cart, only the back office? Write it down: it's the first clue.
4. Take a screenshot of what you see, with the page address visible.

How do I see the real error behind the blank screen?

PrestaShop has a debug mode that, instead of the blank page, shows the full error message. That message usually tells you which file or which module has failed.

If the back office still opens, turn it on under Advanced Parameters > Performance > Debug mode. If it doesn't open either, it has to be done by editing a file via FTP; it's explained in the final section for your technical team.

An important warning: with debug mode on, your customers see the errors too. Only use it for as long as you need to read the message, then switch it off again.

The other source of clues is the error log: PrestaShop saves errors in your shop's var/logs folder, and your hosting usually has its own PHP error log in the control panel.

Can I fix it myself without knowing how to code?

Sometimes, yes. There are three checks you can do without touching any code:

Clear the cache

In the back office, under Advanced Parameters > Performance, click Clear cache. If the back office won't open, your technical team can clear it by deleting the contents of a folder. It's safe: PrestaShop recreates those files on its own.

Disable the last module you touched

If the problem started after installing or updating a module, disable it (don't uninstall it) under Modules > Module Manager. If the shop comes back, you know who the culprit was.

Ask your hosting provider if anything has changed

One straight question: "Have you changed the PHP version or any server limit in the last few days?". Each PrestaShop version only works with specific PHP versions, and a change like that can take a shop down overnight.

If it's still the same after all this, stop testing. Every blind attempt means more time with the shop closed and more risk of touching something that was actually working.

How much does it cost to get it fixed?

At BK Modules we offer urgent PrestaShop support: you pay for one hour of a technician's time, €45 (rate as of October 2026), and we get on it. We work 7 days a week. Error 500s, blank screens and a back office that won't open are right at the top of the list of things we fix.

Here's how it works:

1. You pay for the hour. You can tell us what you're seeing, your shop's address and attach screenshots or the error log, but it's optional: you don't need to explain anything to pay.
2. A technician writes to you in less than 12 hours, 7 days a week, with what we see and how we're going to fix it. We'll ask for access to your shop and, if needed, your hosting at that point, through a secure channel. Never in the form.
3. If it's fixed within that hour, you're done. If it needs more, we stop and tell you what's left and how long it will take. You decide whether we carry on; nothing is charged without your go-ahead.

We work with PrestaShop 1.6, 1.7, 8 and 9, and your invoice is in your account as soon as you pay. We're the people who build PrestaShop modules, so we know from the inside what tends to break.

How do I stop it from happening again?

Most of these errors come from an update applied without testing or a server change nobody warned you about. Having someone who knows your shop and tests updates before applying them avoids almost all of these scares.

That's what annual PrestaShop maintenance is: tested updates, backups, monitoring and hours over the year for when something goes wrong.

For your technical team

If the back office won't open, debug mode is enabled in config/defines.inc.php, changing false to true on this line:

define('_PS_MODE_DEV_', true);

• Logs: the shop's var/logs/, plus the server's PHP error log.
• Cache: delete the contents of var/cache/prod/ and var/cache/dev/.
• Suspect module with no back office access: rename its folder in modules/ so PrestaShop doesn't load it.
• Memory: PHP memory_limit of at least 256 MB.
• Permissions: folders 755 and files 644, with var/, img/ and upload/ writable by the web server user.
• PHP: check that the active version is compatible with the installed PrestaShop version.

When finished, set _PS_MODE_DEV_ back to false.

Want someone to get on your shop right now?

Every hour your shop is down is sales going to another website. Pay for the hour, and a technician who knows PrestaShop inside out will write to you in less than 12 hours to get it back up and running.

Fix my shop for €45