It looks like it cannot spawn a child process? protoc compiler is not downloaded to ~/.pact/plugins/protobuf-0.1.8 so I copied it from my local machine

root@e3116ee8672e:~/.pact/plugins/protobuf-0.1.8# ls -la
total 29040
drwxr-xr-x 1 root root     4096 Aug  5 15:12 .
drwxr-xr-x 1 root root     4096 Aug  5 14:11 ..
drwxr-xr-x 2 root root     4096 Aug  5 14:14 log
-rw-r--r-- 1 root root      309 Jul 15 14:13 pact-plugin.json
-rwxr-xr-x 1 root root 28004704 Jul 15 14:13 pact-protobuf-plugin
drwxr-xr-x 4 root root     4096 Aug  5 15:12 protoc
-rw-r--r-- 1 root root  1699854 Aug  5 15:12 protoc-3.19.1-linux-x86_64.zip
root@e3116ee8672e:~/.pact/plugins/protobuf-0.1.8# ^C
root@e3116ee8672e:~/.pact/plugins/protobuf-0.1.8#