How do I increase number of open files with ulimit on Ubuntu 18.04?

Question

When I try to ulimit -n 4097 or greater I get the following error:

bash: ulimit: open files: cannot modify limit: Operation not permitted

None of the solutions at How do I increase the open files limit for a non-root user? seem to work or apply.

I can raise the limit to 4096 but not beyond.

Output of ulimit -n -H 4096

Edit:

Problem solved:

https://superuser.com/questions/1200539/cannot-increase-open-file-limit-past-4096-ubuntu