The attached simple class can be run and h2load executed against it with the following parameters: h2load -n 10000 -c 25 -m 25 -d test.txt http://localhost:8080 For testing purposes, test.txt was around 70kb in size, but the issue exists for larger and smaller files, although it may take more or less time to hang all threads - and for smaller files the -m (MAX_CONCURRENT_STREAMS) parameter may need increasing to see the issue. We've only tested on Linux - CentOS 9 and Ubuntu 22, as we haven't yet gone to the trouble of trying to build h2load on Windows.  Please note that running h2load using HTTP/1.1 (--h1 flag) requests works without issue.