No graphs are showing after upgrading PHP to 8.5

I upgraded PHP from 8.3 to 8.5

validate.php hangs here

librenms@srv-librenms:~$ ./validate.php

Component Version
LibreNMS 26.9.0-dev.72+613ee5737e (2026-09-04T06:31:22+02:00)
DB Schema 2026_07_30_162514_add_device_refresh_config_permission (397)
PHP 8.5.10
Python 3.10.12
Database MariaDB 10.6.22-MariaDB-0ubuntu0.22.04.1
RRDTool 1.7.2
SNMP 5.9.1
===========================================

[OK] Composer Version: 2.10.3
[OK] Dependencies up-to-date.
[OK] Database Connected
[OK] Database Schema is current
[OK] SQL Server meets minimum requirements
[OK] lower_case_table_names is enabled
[OK] MySQL engine is optimal
[OK] Database and column collations are correct
[OK] Database schema correct
[OK] MySQL and PHP time match
[OK] Active pollers found
[OK] Dispatcher Service not detected
[OK] Locks are functional
[OK] Python poller wrapper is polling
[OK] Redis is unavailable
[OK] No errors found with polling frequencies.
[WARN] IPv6 is disabled on your server, you will not be able to add IPv6 devices.

LibreNMS (with Apache) seems working but no graphs are displayed.

In /var/log/apache2.log I found

AH01071: Got error ‘PHP message: \x1b[31mPHP Error(2)\x1b[0m: file_put_contents(/opt/librenms/storage/framework/sessions/ByQCJciDvuFBlN1KQRuROG3StaTiUBXFtCtm2N6I): Failed to open stream: Permission denied from vendor/laravel/framework/src/Illuminate/Filesystem/Filesystem.php:204 in /opt/librenms/html/index.php:51’

Any hints?

Solved by myself:

usermod -a -G librenms www-data

Will you be able to share the upgrade steps to HPH to version 8.5.10? When I did the upgrade, the CPU usage became very high, and it is slowing the server

thank you very much