Invalid character in header content ["Host"] Postman

Question

When i try to test api with localhost:[port] it gives the invalid character in header ["Host"] console error. I am using dotnet core webApi. I cross checked the CORS configuration from api end it is fine. The issue is on the Postman side. Postman version: v8.7.0

Answer 1

I had the same error being reported for any forked or created Postman requests:

Error: Invalid character in header content ["Host"]

The request URL was using a global parameter:

{{BaseUri}}/some/sort/of/resource

In the console logs the following was reported (URLs redacted):

Request Headers
User-Agent: PostmanRuntime/7.29.0
Accept: */*
Cache-Control: no-cache
Postman-Token: 9d14e81d-1e21-44a2-93ed-2758f0ad24fa
Host: my.url.co.uk↵
Accept-Encoding: gzip, deflate, br
Connection: keep-alive

Note the ↵ character at the end of the Host Header.

The global BaseUri parameter did not appear to have a line break at the end of it. However, completely deleting said parameter and recreating it seems to have fixed the issue.