How does one Change the Maximum Query String Length in AD FS V4 Server 2019?

Question

How does one Change the Maximum Query String Length in AD FS V4 Server 2019?

Lance Merchant 1

Here's how to if the server has IIS (https://www.saotn.org/the-length-url-request-exceeds-configured-maxurllength-value/) but the newer AD FS versions do now have IIS.

Pierre Audonnet - MSFT 10,191 Reputation points Microsoft Employee

2022-04-14T16:17:37.05+00:00

I am curious, what is the scenario in AD FS where you hit this limit?
Lance Merchant 1 Reputation point

2022-04-15T12:27:25.033+00:00

Apparently canvas logout urls are really long

https://community.canvaslms.com/t5/Canvas-Integration-Documents/Configuring-ADFS-SAML-and-Canvas-Authentication/ta-p/387381

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Pierre Audonnet - MSFT 10,191 Reputation points Microsoft Employee

2022-04-14T16:17:37.05+00:00

I am curious, what is the scenario in AD FS where you hit this limit?
Lance Merchant 1 Reputation point

2022-04-15T12:27:25.033+00:00

Apparently canvas logout urls are really long

https://community.canvaslms.com/t5/Canvas-Integration-Documents/Configuring-ADFS-SAML-and-Canvas-Authentication/ta-p/387381

Answer 1

The documentation is erroneous. You should not set the URL of the AD FS WS-Federation logout endpoint as a SLO endpoint for an application. This is creating issues and potential security risks (making you think you signed-out from everywhere when you do an IDP initiated sign-out or a SLO from another SP, when in fact you haven’t).

Regarding the way to configure the HTTP driver, you may use this reference: https://learn.microsoft.com/en-us/troubleshoot/developer/webapps/iis/iisadmin-service-inetinfo/httpsys-registry-windows the value MaxFieldLength and/or MaxRequestBytes seem to allow you to customize some maximum lenghts.

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How does one Change the Maximum Query String Length in AD FS V4 Server 2019?

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