Workflow Manager Fail with “Trusted provider is missing” error

I encountered this problem with a customer where one of our workflow heavy applications stopped to function .

The error I got within ULS Logs look like

00000003-0000-0ff1-ce00-000000000000  trusted provider is missing

Turns out it is a security change to the IIS Application for the “Workflow Management Site” where the Authentication provider included

Asp.Net Impersonation Enabled 
Along with other changes to that IIS application .


This customer is using SharePoint 2013 Enterprise on premises with NTLM only in a windows integrated mode , no SSL .

After narrowing down the issue to “Authentication problem” I did setup a new WFM with OOB configuration.

Asp.Net Impersonation Disabled 

I have checked all those settings below this will fix this issue after you restart the application pool.

See Below

Best of Luck.