Flow designer Rest API call with Basic auth. report auth failed, but works in Postman

[William Mo]

I am trying to use Flow Designer Rest Step to call a API with basic auth. Here is the result from Postman. It is working fine.

Here is the snapshot in the flow designer

here is the API response

could anyone share some ideas?  and how could I retrieve the header info in the header after the call returned successfully? 

[Petr Pastuszek1]

Hello,
I had a similar issue.
In Flow Designer, the REST Step to run REST message requires to provide connection and credential aliases as of basic authentication.
Once I have completed this step and imported REST message in REST Step, I got all the time response code 400 back.
Several hours I tried to debug and at the end I found this.

Basic authentication require user name / password
user name field is max size 40
Supplier provided me with user name long 48 characters.
I increased field size and updated basic authentication record with the full user name again.
All started to work.

PS: What helped was to run REST via background script and than I compared HTTP outbound log with HTTP outbound log created by REST called from flow designer, string of Authentication value from HTTP header started to be the same but after 50 characters changes which helped me to understand and debug this field max size issue.

Hope this post helps to someone

/Petr