knxd backend handler might fail

[ChristianMayer]

• A badly configured docker container (e.g. bad KNX tunnel port) creates an error message that the user might not understand and thus can not help himself
• for whatever reason a request with "i=unknown" could happen (see https://knx-user-forum.de/forum/supportforen/cometvisu/1340421-cometvisu-11-0-portainer-timberwolf-protokollfehler-backend-invalid-response?p=1341162#post1341162 )

[asander81]

In my case the reason for this error is, that the answer from backend is "{'error': 'Read failed'}". So there is something going wrong in eibread-cgi.

[ChristianMayer]

@asander81 I guess that you are using a knxd newer than version 0.0.5.1? Just knowing about the latest knxd version (I never checked any in between) I found a few issues to be aware of: knxd/knxd#494, knxd/knxd#495 and knxd/knxd#493
A {'error': 'Read failed'} is coming from the knxd and eibread-cgi/eibwrite-cgi, so it's not a topic for this issue here.

[ChristianMayer]

Current level is fine for 0.12.0, any additional optimization should come for a later release