When users try to approve pending approvals on the portal, SSO Dialog window is not popping up. Rather it automatically approves/rejects the record based on the Approval or Reject Selection.
Madrid Patch 9
When we try to approve from portal, createSsoReauthenticationUrl function in ESignatureUtils script includes is called, which in turn calls the script includes named SAML2_update1_esig. There is a new version of this script includes in Madrid Patch 9. If this script includes is modified, it would be skipped during the upgrade causing the issue.
Merge the changes of the SAML2_update1_esig script includes to the out of box version to resolve the issue.