Hi Robert,
I've created a build tool that use jshell to read its configuration file, for that i run jshell using the javax.tool.Tool API.

Since jdk13, jshell fails to connect to the remote VM.
I'm not able to reproduce the case locally but it can reproduce the issue using TravisCI and CircleCI,

Here is the execution in CircleCI:
https://circleci.com/gh/forax/pratt_parser/3

And the one in TravisCI:
https://travis-ci.org/forax/pratt_parser/jobs/511498907

In both cases the error is the same, it timeout.

I wonder the issue is not a change in the attach API that jshell is using.