Hi, after a long bit of working on this issue.
I am quite certain that it is caused by setting a valid certificate in the configuration.
It happens when you configure it directly in the fusionauth.properties file ssl. Everything appears to work, then you find out you cannot create or edit tenants, and other areas do not work randomly. I would just get at no response in the browser and then this buffer overflow in your logs.. I struggled for quite some time with this. Just writing here so if someone else comes to this point.. Just stop and install a reverse proxy problem solved.
I also think honestly fusionauth's quick guide should include setup with caddy and/or nginx with ssl certs. Really I think it would be best to remove ssl setings and force users to setup a reverse proxy as it is simple to do. But I see that you maybe want flexibility here. I have done this now with Caddy and it works flawlessly.
Thanks again for a great product though and great community support.
Authfusion is by far the easiest alternative to Indentity Server for .net and probably the easiest auth server I found.