How to debug the Citrix ICA error "The session limit has been reached"?

Apologies in advance for somewhat vague information. I am new to Citrix XenApp/XenDesktop technology and am just looking for generic troubleshooting information.

At my place of employment we have kiosks that are configured to connect to a SaaS webapp. These kiosk have either the Citrix XenApp or XenDesktop installed.

One of the icons launches the IE browser that connects to the SaaS app using a preconfigured user account. Sometimes, however, instead of launching the browser, the system displays the "The session limit has been reached. Please contact your system administrator." error shown in below image.

The people administering these kiosks think that this message comes from the SaaS web application but that application does not enforce any limits on how many session are open for a given account under a given time.

Also considering how Citrix XenApp/XenDesktop works I would think (but maybe I am wrong) that if the SaaS app did reject a user login, we would be displayed an error message in Internet Explorer instead of this ICA prompt.

So I think that the issue here could be that the message is not about login sessions made to the background SaaS app but either about Citrix sessions or perhaps previous IE browsers somehow running in the background(?)

However our company's Citrix team looked at this and noticed that "Citrix was still active" when this prompt was displayed. The conclusion was then that Citrix is for that reason not the cause here.

So I wanted here to ask some questions on what things I could consider as causes and where I could look in the hopes of getting started on this issue.

This would be for XenApp / XenDesktop 7.18.

The questions I have:

1. Does XenApp / XenDesktop have log files that can be consulted for debugging issues like this?
2. Is it possible to get XenApp / XenDesktop to run in debug mode (to output more details to the log files)?
3. Does Citrix have configuration settings that could lead it to have an issue like this?

A. First check the event logs and see when you facing this issue so does any event logs generated.

B. Also you can check the ICA configuration tool for session settings and checked if session settings are set to NEVER.

C. The ICA listener configuration tool is located at Start > All Programs > Citrix > Administration Tools > ICA Listener Configuration.