Caught an exception while invoking the load-balancer agent

Hi Everyone. I am trying to increate the timeout on the load balancer. I am using the latest version on Zato on docker.
The default value is 15000ms. I would like to increase connect, client and server on to 300000ms. Sadly I receive the following error

Caught an exception while invoking the load-balancer agent, e:`<class 'LookupError'>:unknown encoding: wb`

A little help for you would be great. Thank you very much :grinning: :grinning:

Thanks for reporting it, this is corrected now. Please use the latest image:


thank you very much! I have downloaded thet latest image. But I got the same error. But when i try to reenter the value anotheur time i got the following

Caught an exception while invoking the load-balancer agent, e:`<class 'Exception'>:Caught an exception, e:`Traceback (most recent call last):
  File "/opt/zato/3.2.0/code/zato-common/src/zato/common/", line 150, in validate_haproxy_config
    timeouting_popen(command, HAPROXY_VALIDATE_TIMEOUT, timeout_msg, rc_non_zero_msg, common_msg)
  File "/opt/zato/3.2.0/code/zato-common/src/zato/common/util/", line 1635, in timeouting_popen
    raise Exception(msg)
Exception: Failed to validate the config file using HAProxy. config_file:``command:[['haproxy', '-c', '-f', '/tmp/zato-tmpmipugzo0']], return code:[2], stdout:[b'Configuration file has no error but will not start (no listener) => exit(2).\n'], stderr:[b''] 

I have checked twice. Delete the previous image and download the new one.

Thank you very much


the load-balancer is an embedded instance of HAProxy. What you are getting here is a message from HAProxy saying that the config file that Zato generated is for some reason rejected.

Try to find out why it is the case, in the message from your screenshot, you can see the command that is run as well as where the config file is in, and you can try to reproduce it and find a root cause independently of Zato.



We have updated our HAProxy setting and use the latest image. But we are now facing another error while increasing Zato time out

Caught an exception while invoking the load-balancer agent, e:`<class 'TypeError'>:write() argument must be str, not bytes`

I have tried to edit the time out using the GUI view but nothing has changed

Hi Everyone!

Could we have any feedback on this issue please. We still have problems to increase timeout on Zato (We use Zato on Docker). A little help would be great.

Thank you again guys

Hello @louistwiice,

there has been no progress on that matter yet, I will update this thread once the situation is resolved.


This is done, please update to the latest version:

1 Like

Works perfectly @dsuch . Thank you very much