Error "The message is not an HTTP POST." using ADFS-MVC example when logging out

Dear ComponentSpace team,

trying to make your ADFS-MVC SP example work with our ADFS 4.0 server we suceeded with logging into the demo app.
But when hitting the Log Off link, the browser shows the error “The message is not an HTTP POST.” and we are not getting logged out.
No further error is recorded on ADFS side.

Part of the saml log shows:

2019-10-11 15:24:34.968 VERBOSE (0)[60] : Receiving response over HTTP POST
2019-10-11 15:24:34.968 VERBOSE (0)[60] : HTTP request:
GET /Account/Logout HTTP/1.1
Connection: keep-alive
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
Accept-Encoding: gzip, deflate, br
Accept-Language: de,en;q=0.7,en-US;q=0.3

Could you please help with this?

Thank you.

A SAML logout message can be received in either an HTTP Get or HTTP Post so it’s strange you’re seeing that message as part of SAML logout.
Please send the entire log file, showing the successful SSO and failing SLO, as an email attachment to mentioning your forum post.