Hi All, I have been dealing with this issue where I am able to call an API through Postman but when I do it through UiPath, the NTLM authentication does not work. I am not doing windows authentication, I am doing negotiated authentication with custom credentials since we have a service account crede…

$uri = “ https://your-api-url ” $sec = ConvertTo-SecureString “Password” -AsPlainText -Force $cred = New-Object System.Management.Automation.PSCredential(“DOMAIN\Username”, $sec) $response = Invoke-WebRequest -Uri $uri -Method Get -Credential $cred -UseDefaultCredentials:$false $response.Content …

Are you doing this in Studio on your machine logged in as you, or from a robot server as a service account?

@Denisha_Lamsal Please try this: Find this setting in the HTTP Request activity and set it to True: [image] Then test the request with the Test button (make sure everything is hard coded, because it won’t work with variables for this Test button) [image] The report section will now be filled wi…

Hi, this is what I see: [Status] 401 Unauthorized [Headers] Cache-Control: private X-AspNet-Version: 4.0.30319 WWW-Authenticate: NTLM, Negotiate X-Frame-Options: SAMEORIGIN Strict-Transport-Security: max-age=31536000 Date: Tue, 13 Jan 2026 16:56:53 GMT [Content Headers] Content-Length: 0 …

Yes, in studio on my machine logged in as me. I also tried it from a server but it did not work there either.

Is your Studio installed in user or service mode? You can check in Studio on the Start tab at the bottom. For example mine looks like this: [image]

Mine says Per-User installation

Ok sounds like you’re installation is correct. I was just wondering if it was trying to use the service account for authentication rather than your user.

Hi @Denisha_Lamsal UiPath handles NTLM differently than Postman. Use HTTP Request → Windows authentication → Custom credentials, pass the username as DOMAIN\username, and try with PreAuthenticate disabled. Also make sure the robot machine has domain/network access to the API.

[image] Denisha_Lamsal: [Status] 401 Unauthorized [Headers] Cache-Control: private X-AspNet-Version: 4.0.30319 WWW-Authenticate: NTLM, Negotiate X-Frame-Options: SAMEORIGIN Strict-Transport-Security: max-age=31536000 Date: Tue, 13 Jan 2026 16:56:53 GMT [Content Headers] Content-Length:…

Ah okay I see that now. I am now seeing: 401- Unauthorized: Access is denied due to invalid credentials. You do not have permission to view this directory or page using the credentials that you. Issue is that these credentials are working via Postman.

HTTP Request - NTLM Authentication not working

Help Activities

Denisha_Lamsal January 16, 2026, 3:37pm 19

Thank you Monali. I tried the Powershell script but am still getting errors saying “Invoke PowerShell: Cannot process argument transformation on parameter ‘Credential’. userName”.

Topic		Replies	Views
NTLM authentication in HTTP request Studio api	7	1191	September 11, 2025
How to pass NTLM authentication credentials for HTTP request using UIpath Studio Studio	2	1499	February 24, 2022
How to call a post webservice with NTLM Authentication bypassing the credentials Studio studio , question	8	3122	May 20, 2021
How to setup NTLM authentication when logging into orchestrator API Help	1	1565	June 29, 2019
NTLM Webservice Authentication Help	1	1000	July 31, 2019

HTTP Request - NTLM Authentication not working

Related topics