[Tue, 15 Sep 2015 12:50:08GMT] [symc_iis7_plugin.dll] [Process:8480][ERROR] : invalid otp token value for user <Domain\Userid
When the Exchange Server was upgraded from 2010 to 2013 users were not able to login with “invalid otp token value for user <Domain>\Userid” errors. The client had followed the procedure correctly in the PartnerIntergration_IIS7.PDF guide but still continued to have the login issue.
User had to change the “Forms authentication for OWA in Exchange” to just prompt for Username, instead of Domain\Username.
Exchange server upgraded to 2013
Procedure for OWA found in the PartnerIntergration_IIS7.PDF guide page 22 Customize the Log-in Page for Outlook Web App (OWA) for 2013 was followed correctly
Customize the Log-in Page for Outlook Web App (OWA) for 2013
1 Make a back-up of the log-in page (typically logon.aspx). Open this file using any text-editor.
You can locate the logon.aspx page at C:\Program Files\Microsoft\Exchange