AppApi HaRP Proxy connects but Test-Deploy fails on Heartbeat with 404

In my case the HaRP Proxy started but was not reachable for the nextcloud (404 not found testing http://MY-NC-LOCAL-IP:8780 )

I tested both configs from here:

https://github.com/nextcloud/HaRP

both not working for me. So i investigated the logfiles and found this

Deploy daemon "harp_proxy_host" is not accessible by Nextcloud. Please verify its configuration

followed by

ClientException 

Client error: `GET http://MY-LOCAL-NC-IP:8780/exapps/app_api/v1.41/_ping` resulted in a `400 Bad Request` response: {"message":"client version 1.41 is too old. Minimum supported API version is 1.44, please upgrade your client to a newer (truncated...)

Could not connect to Docker daemon via http://MY-LOCAL-NC-IP:8780/exapps/app_api/v1.41/_ping

docker –version delivers 29.x and an existing ONLYOFFICE docker solution works with that for years now.

Never the less found this thread and i hope it will help others to figure out what’s going wrong…

https://github.com/nextcloud/HaRP/issues/69

The workaround was /is to edit the docker.service file and append following ENV variable

[Service]
Environment=...
Environment=DOCKER_MIN_API_VERSION=1.41

After a systemctl restart docker and a restart of my nc (nginx) the connection between HaRP Proxy and Nextcloud could be established, followed by a successful test-app deployment!

As mentioned, i hope this may be helpful for others starting with AppApi or having those probs after a docker update as well.
Cheers!