The status code 139 typically indicates a segmentation fault on Unix-based systems, which can be caused by the process trying to access an illegal memory location. However, the document that I found does not directly mention this error code. Instead, it discusses issues surrounding an agent's ability to communicate with the Prefect server, and flow runs getting stuck in a pending state.
If you are seeing the message "Flow run infrastructure exited with non-zero status code 139" in the context of using Prefect 2.x, this might suggest there was a crash within the infrastructure that was running the flow, potentially linked to a problem with memory access or other resources inside the environment running the flow, such as a container. It's possible that similar users have encountered this challenge and discussed it in the Prefect community or possibly reported it as an issue on GitHub.
If you would like me to search for relevant GitHub issues, please let me know, and I can assist with that as well.