I have a strange situation with my work project (Leiningen + lein-figwheel), with four different behaviours on four different machines. Let’s call them A, B, C and D . A. I can only start the project with repl :headless, otherwise I get: REPL server launch timed out. regardless of how long I allow the timeout to be. Starting it headless I can’t start figwheel. I get Execution error (IllegalArgumentException) at figwheel-sidecar.utils/illegal-argument (utils.clj:53) when it tries to require the namespace with my figwheel :ring-handler. B. I can start the project with an interactive repl. And then also start fighweel from that repl. However if I start the repl :headless I get the same error as with A when trying to start figwheel. C. I get the same timeout error as with A starting with an interactive repl. But I can start it headless, and I can start figwheel from the headless repl session. D. I can start the repl interactive or headless and also start fighweel regardless. It is all Macs with latest macos and all are using Java 8 (because reasons). Not sure where to post this, but figured that in this channel there is the knowledge that might help me pinpoint where the problem stems from.