FormatException Expected 4 colon-separated fields, got 3 OK

Hi , when im starting a job with proxy api give to me this error

FormatException Expected 4 colon-separated fields, got 3 OK

When i use proxy from group start .

Btw, sorry for my bad english, thx for any response

Can you give an example of a line that comes from the API? Maybe the password is missing and there is only username?