I found what was the issue.

There was indeed something happening in the audit portal. Each attempt of the page was adding a line in this page :

I added the role of the application /terminalsocket to %All and now the error is gone. I have no clue why this happened though, your package didn't seems to change this kind of parameters (Or maybe I missed it).

In any case, thank you for your help !

I tried these operations.

There was no /terminalsocket indeed in the web session portal before I launched a new session. However, this session does not disappear when I close the page. It even create another session for each attempt it make, so every 10 seconds. After waiting a bit (like 5 - 10 minutes), some begin to disapear.

It doesn't show more than the error message saying it can't connect, but it seems it use the 4.9.5 version, I found this in the index.js source file :

I notice the user is UnknownUser. Could this have an impact ?

There might be something happening here indeed :

License Unit Use  Local  Distributed 
Current License Units Used 35 35
Maximum License Units Used 35 65
License Units Authorized 64 64
Current Connections 39 43
Maximum Connections 39 71

I'm not sure about the difference between local and distributed, but if seems like it exceed the maximum units authorized in the distributed part. Could that be the problem ?

If it is, how can we solve that, granted that before the update, the problem wasn't here ? I assume there might be some licence management we can do in this case.

So far I don't think our license is consumed since we can still use the entire product without any limitation. Or did I missunderstand the meaning of "license to be consumed" ?

Also, we're not using Docker version of Intersystems. And the two environments I mentionned are on the same machine. So there is two instances of Iris running on a windows server.

Indeed, I also compared these two, and they are identical.

However, I noticed this file : web.config appeared at the root of CSP folders. It seems to contain no settings whatsoever since there is only this in it :

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
</configuration>

This is the only difference I found so far between the two environments.

Also, maybe I should precise that the 2 environments are on the same server, so two instances of Iris runnning at the same time on the same machine (same version of course). Since one of them still works, I assume it is an Intersystems setting issue.