How to Update the PHP Version in Plesk (Safely, Per Site)
To update the PHP version in Plesk, open the domain, then PHP Settings, choose the version, and apply. Change one site, reload it, and use the same screen to roll back if it breaks. The dropdown lists only the versions your host installed — if one is missing, ask the host to add it.
The safe per-domain upgrade routine for Plesk Onyx and Obsidian: compatibility check, PHP Settings switch, verify, roll back.
knowledge
- Read time
- 4 min
- Sections
- 6
- Updated
- 14 Nov 2026
- Written by
- WebJi® team
Last editorial update: 15 November 2026.
Why is an outdated PHP version a security risk?
Each PHP branch gets two years of active support and two more of security fixes — after that, nothing, and every vulnerability found in an end-of-life version is public and scanned for at scale. As of 15 November 2026, PHP 8.2, 8.3, 8.4 and 8.5 are supported (8.2 only until 31 December 2026), while 8.1, 8.0 and every 7.x line are end-of-life.
The secondary costs compound: newer PHP runs faster on the same server, and current themes, plugins and frameworks refuse old interpreters, so an outdated version blocks the site's next update too. The routine below — compatibility check, change, verify, roll back — makes the upgrade a five-minute risk instead of a gamble. Big jumps deserve a rehearsal; the WordPress staging guide sets one up.
Step 1: what do you check before changing PHP?
Note the current version on the site's PHP Settings screen first — that string is your rollback point — then inventory every plugin, theme and piece of hand-written code running on the site.
- Record the current version: Websites & Domains → domain → PHP Settings shows it at the top.
- Update first: on WordPress, push plugins, themes and core to their latest releases before the PHP change — that removes most incompatibilities in advance.
- Check the abandoned ones: anything unmaintained for years is the usual cause of a broken upgrade; replace or remove it before you switch.
- Take a fresh backup: the Plesk Backup Manager guide covers the click path, so a bad surprise costs minutes, not the site.
Step 2: how do you change PHP in Plesk PHP Settings?
Open Websites & Domains, open the domain you are changing, and click PHP Settings — on newer Plesk Obsidian panels the domain card shows a PHP button with the current version beside it.
- Keep the PHP support checkbox ticked.
- Pick the target version from the dropdown — a current 8.x release is the safe default.
- Leave the handler (FPM or FastCGI) as configured unless support has advised otherwise.
- Click OK. The change applies to that domain only and takes effect shortly; the domain card then shows the new version.
The dropdown lists only the versions your host has installed on the server. If the one you want is missing, ask the host to add it rather than settling for an older line — on WebJi® Plesk hosting the maintained 8.x lines are installed per server.
Step 3: how do you test and roll back?
Reload the site in a private browser window — so cache cannot hide the result — and walk the pages that matter: front page, a product or article page, the contact form, and the admin login. A working site finishes the job; repeat the same three steps on the next site when you have several.
Anything broken — a white screen, a fatal-error message, a form that dies — is fixed the same way it was made: back to PHP Settings, re-select the previous version you noted in Step 1, click OK, and the site is back within moments. Then read the error text: a named plugin or theme usually identifies the culprit, which you update or replace before retrying. If the error means nothing to you, email support@webji.services with the exact message — the 24/7 desk reads it in Hindi or English, average first reply under 60 minutes. WordPress sites can also expose the detail through the error-log guide.
Can different sites run different PHP versions?
Yes — PHP is selected per domain in Plesk, so the shop can run a current 8.x release while an older site keeps the version it was built on until its rebuild is scheduled. Subdomains inherit the parent domain's version unless you set theirs separately, so a change on the main site reaches its subdomains by default.
Treat mixed versions as a staging post, not a destination: every site still on an EOL line carries risk, so schedule the stragglers. When everything is current, keep it that way — ask when a new PHP line lands on your server and test each site once. The Plesk WordPress Toolkit can run those updates and the version switch from one screen.
Frequently asked questions
How do I update the PHP version in Plesk?
Open Websites & Domains, open the domain, click PHP Settings, keep PHP support ticked, pick the version from the dropdown and click OK. Do one site at a time and reload it in a private window before moving to the next.
Is jumping from PHP 7.4 to 8.3 safe?
Not blindly — big jumps change behaviour. Update plugins, themes and core first, take a backup, then change one site and test it. PHP 7.4 has been end-of-life since late 2022, so the move is due; the same PHP Settings screen rolls the version back in moments if anything breaks.
Can different sites on one Plesk server run different PHP versions?
Yes. PHP is selected per domain, so one site can run a current 8.x release while an older site keeps the version it was built on. Subdomains inherit their parent domain's version unless you set theirs separately on their own PHP Settings screen.
Why is the PHP version I want missing from the dropdown?
The dropdown lists exactly what your host has installed on that server — Plesk cannot offer a version that was never added. Ask the host to install it; on managed plans that is a routine server-level request, not a site migration.
Why should I update PHP at all if the site works?
End-of-life PHP stops receiving security patches, and its known vulnerabilities are actively exploited by bots. Newer PHP also executes the same code faster and keeps current themes and frameworks installable, so an old interpreter quietly blocks every future update.
Last editorial update: 15 November 2026.
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