This is due to non-ASCII characters in headers causing an issue in the FusionAuth parsing code. Cloudflare sends headers with non-ASCII characters (such as cf-region: São Paulo) which triggers this issue.

This is a java-http bug that was fixed in 2024, and released in FusionAuth version 1.51.2.

So, two options:

upgrade to a version of FusionAuth 1.51.2 or newer. This is the recommended approach, but may require some work. as an interim workaround, you can disable the "Add visitor location headers" option from your CloudFlare console. This should not have any negative impact, since we do not inspect those headers.

@sergey_smirnov Hmm, the 10 sec between the logs does lead me to similar speculation that it is being caused by the user. I would think they would be closer together if it was something the application was doing on its own (although I am not entirely ready to rule that out either).

That being said, it seems like just guessing unless you can get the application logs and trace the users page views for sure. Is that possible?

There is a setting in the Tenants for the Session timeout.
Tenants -> Edit -> OAuth tab -> Session timeout

Screenshot 2025-06-26 at 8.46.22 AM.png

Let me know if you are able to log the users page views.