Problem of random disconections

Hello,

We upgrade our projectoria from a 8.1.5 version to the 10.1.3.
Our environnement :

• Solaris Unix 11.4
• PHP : 8.1
• Mysql : 5.7
• Apache : 2.1

The migration went well. We got all our data so all is fine.
All is working well except one thing : randomly we have lot of disconections. For example for 10 min, all work great and suddenly the next 5 min, we can't connect anymore, we have these messages : "Connection lost. Thank you to login again."
When we try to login again, we can't connect, same message for like 4/5 times, and we succed to login.
And sometimes we have the message :
"An anomaly has occurred with the current session.
Refresh the page or close the browser and try again.
Also check that cookies are allowed.
If the problem persists, contact your administrator."
After this message which is different than the other one, wWe have to refresh completely or clean the cache/cookies, for the website to work again. 

No errors in the log file at the script level. No error in PHP. In Appache we have this error : "PHP Warning:  session_start(): Failed to decode session object. Session has been destroyed in /usr/local/projeqtor/tool/projeqtor.php on line 47, referer: [url=http://172.26.201.190:82/view/main.php?lostConnection=true&csrfToken=]projectoria.url:84/view/main.php?lostConnection=true&csrfToken=[/url]
It seems to work better and more stable with Firefox than Chrome but it still happens after a moment. 
We try with a blank database in case, but same problem. 
We are actually trying to a full fresh installation in a full new environnement, but we think it will change nothing because we think it is a parameter in PHP or Apache witch is bad.

Do you have any ideas or clues or even a solution about this problem please ?

Thank you !

Hello.

More news.
We try a fresh instal with a new database. (Just in cases.) Same errors.
We though it could be the utf8m4, we check all the prerequis, and modify correctly all parameters. Sames errors.
We though we should install 9.5.5 first, in case we did bad with utf8.m4 (who knows) but in fact we have also the same problems in this version who don't use ut8.mb4.

We start to be out of ideas.

In fact, I apologie, we are in 2.4 for Apache. I wrote too quickly the version.

Do you know what is the parameter the most suitable for Projectoria in Apache about the cookie duration ?

Thank you,

We try to install it on a virtual machine on windows with the same version PHP and it works perfectly.

So it seems a problem maybe with Solaris or configuration in Apache or PHP.