We had the same problem on several servers, without doing any updates. I found the solution on plesk server for windows.:
Look for this folder:
C:\Program Files (x86)\Plesk\admin\plib\modules\monitoring\vendor\composer
Open this file:
platform_check.php
Edit:
if (!(PHP_VERSION_ID >= 70400)) {
into:
if (!(PHP_VERSION_ID >= 70100)) {
Refresh your Plesk panel and it works again!
Don't forget to update Plesk and PHP version after.
When i look into the extensions catalog, i found the problem:
Autoupdate with extensions was switched on.
The recently updated monitoring extension was the problem:
2.4.1 (21 October 2022)
- [!] Monitoring v2.4.1 will be the last Monitoring update that supports Plesk versions older than Plesk 18.0.41. To continue receiving Monitoring updates with bugfixes and new features, please update your Plesk installation to version 18.0.41 or higher.
- [-] Logging in to Plesk Obsidian 18.0.35 and earlier with Plesk Monitoring 2.4.0 installed no longer fails with the "Your Composer dependencies require a PHP version >= 7.4.0" error. (EXTPLESK-4019)