Website Shows a 500 Internal Server Error After a PHP or Hosting Upgrade: What to Check
A 500 Internal Server Error that appears right after a PHP or hosting upgrade usually means the server is running, but your website's code, a plugin or a theme failed on the new PHP version or server setup. The one reversible step an owner can take is to switch the PHP version back in the hosting control panel, if the host offers that, after noting the current setting.
This guide is for an owner whose developer is unavailable. Nothing in it asks you to edit code, touch the database or delete files. Entrant Technologies builds websites and web applications, and these are the steps we would want an owner to take first.
What does a 500 Internal Server Error mean after a PHP or hosting upgrade?
It means the server received the request but hit a problem it could not handle, so it sent an error instead of your page. MDN describes the 500 Internal Server Error status as an "unexpected condition that prevented it from fulfilling the request" and as a generic "catch-all" response.
The code says where the problem is, not what it is: on the server, not in your visitors' browsers. MDN lists improper server configuration, out-of-memory problems, unhandled exceptions and improper file permissions among the causes. If it began right after an upgrade, the upgrade is the first suspect.
Why does a PHP version change break a website that worked yesterday?
Each major PHP version removes old features and makes the language stricter, so code written for an older version can stop with a fatal error on a newer one. PHP runs WordPress, Laravel, Magento and many custom websites.
The PHP manual's list of backward incompatible changes in PHP 8.0 shows how. Functions such as create_function() and each() were removed, and several situations that used to produce only a warning now throw an error that stops the page. One old plugin calling a removed function can take down every page that loads it.
Why did my host change the version at all?
Hosts retire PHP versions that no longer receive security fixes. According to the PHP supported versions page, each branch gets two years of active support and two more of security fixes only. As of October 6, 2026, the supported branches are PHP 8.2, 8.3, 8.4 and 8.5, and security support for 8.2 ends on December 31, 2026.
What can I safely check in about 10 minutes?
You can gather the facts a developer or the host's support team will ask for, without changing anything.
- Open the site in a private browser window and on a phone using mobile data. Note the exact error wording and the time.
- Check which pages fail: the home page, an inner page and the admin login.
- Search your inbox, including spam, for recent emails from the hosting company. Upgrade notices usually name the old PHP version, the new one and the date.
- Check the host's status page for an incident, and the billing page to confirm the plan is active.
- Log in to the hosting control panel, find the PHP version setting (see the next section) and write down what it says.
- If the panel has an error log viewer, take a screenshot of the most recent lines. Change nothing.
How do I see which PHP version my hosting panel is set to?
Look for a PHP setting in the software or domains area of your hosting control panel; it shows the version each domain uses.
In cPanel, the screen is called MultiPHP Manager. It lists each domain next to the PHP version it currently uses. cPanel notes that the hosting provider can enable or disable this screen, so you may not see it.
In Plesk, go to Websites and Domains, find the domain and click PHP, as described in the Plesk PHP settings guide. Plesk states that you may be able to manage only some of these settings, or none, depending on your subscription. Other panels usually have an equivalent page; search the host's help center for "change PHP version".
Is it safe to switch the PHP version back myself?
Yes, if your host offers a version selector, because it is a single setting that you can return to its current value on the same screen. It does not alter your content or your database. Treat it as a temporary measure, not a repair.
First write down the version shown now. Then select the version the site ran on before the upgrade (the host's notice email usually names it), apply, wait a few minutes and reload the site in a private window. In cPanel, tick the domain, choose from the PHP Version menu and click Apply. If the site returns, tell your developer what you changed and when.
If the error stays, set the version back to the value you wrote down and stop. Do not try other versions or other options. If the old version is not listed, the host has removed it and the code needs updating instead.
What should I not do when my site shows a 500 error?
Do not make changes that cannot be undone with one click, and do not make several at once.
- Do not edit code or configuration files.
- Do not delete or rename folders, and do not run database repairs.
- Do not restore a backup yourself; it can overwrite orders, enquiries and content added since it was taken.
- Do not switch on error display for the live site. The PHP manual says display_errors "should never be used on production systems" and advises logging instead.
- Do not change DNS records or move hosts in a hurry; the same code fails on the same PHP version elsewhere.
When should I call a developer, and what should I have ready?
Call a developer if the version cannot be switched back, if switching back did not help, or if it did: the code must still be made compatible before the old version is retired. Also ask the host's support team what changed on your account and when.
Have this ready:
- The time the error started and the pages affected.
- The host's upgrade notice, plus the PHP version before and now.
- Any change you made yourself, including a switch back.
- Screenshots of the error and of the error log, if you found one.
- What the site is built on (for example WordPress, Laravel or custom code) and when it was last updated.
How do I stop this happening again?
Keep the site's code on a supported PHP version before the host forces the change: read hosting emails, have someone update the platform, plugins and custom code a few times a year, and test each new PHP version on a staging copy first.
Our guide to software maintenance and support explains what an ongoing arrangement normally covers.
Quick answers
What does a 500 Internal Server Error mean?
It is a generic server-side error: the server hit an unexpected condition and could not produce the page. It does not identify the cause, and it is not a problem with the visitor's browser.
Why did my website break after a PHP upgrade?
Newer PHP versions remove old functions and treat more mistakes as fatal errors. Code, plugins or themes written for an older version can stop running, and the server then returns a 500 error.
Can I switch the PHP version back myself?
Often yes, if your host provides a PHP version selector such as MultiPHP Manager in cPanel or the PHP settings screen in Plesk. Write down the current version first, and treat the switch as temporary.
Is my website data lost when I see a 500 error?
Usually not. After a PHP or hosting upgrade, a 500 error normally means the code failed to run while the files and database are still on the server. Confirm with your host or developer before anyone restores a backup.
How long can I stay on the old PHP version?
Only as long as your host keeps offering it. Each PHP branch receives two years of active support and two years of security fixes, and hosts retire versions past that point.
Conclusion
A 500 error after a PHP or hosting upgrade is nearly always a compatibility problem between older code and a newer server. Note the current PHP version, switch back once if your host allows it, and leave code, files, backups and DNS to someone who can read the error log.
If you have no developer available, you can contact Entrant Technologies and we will take a look.