You cannot login to the Collaboration Hub via SAML and you get the error message "saml2.exception - Uid does not match. Did not authenticate external user".
Provide steps that the user can take to solve the problem. For example "The level 7 printer will flash red when it is out of paper. Add paper to tray 1".
The reason for that is, that the submitted external ID is different to the ID in our database. Please send an email to the Signavio Support containing the information which users (email address) are affected and what changes were made recently on your side.
KBA , BPI-SIG-CA-SEC-SAM , SAML 2.0 for SAP Signavio , How To