KanBo Error: User authentication postback failed (On-Premise Installation)

KanBo Log file shows Error: User authentication postback failed (On-Premise Installation)

If you are getting an error message like this in KanBo, please check the KanBo Log File for further information about it

Plugins         FATAL | plugin 03470f82-ba88-4247-adb5-6babadd84d47(Sharepoint on-premise authentication): An unexpected exception has occured 
EXCEPTION: System.Configuration.ConfigurationErrorsException: Element signer not found in /kanbo/(0)plugins/(3)auth.sharepoint (/)

If the KanBo Log File shows you the error similar to this, please be sure to check the web.config if you did include the Certificate Information. 

Most likely it is not correct or missing completely.

Additionally it is possible that the following error shows up as well in the KanBo Log File.

Security        ERROR | User authentication postback failed (56f6cf25-4353-42a2-b48c-b5eb164d553a):
KanBo.Plugins.Infrastructure.FactoryNotFoundException: Factory not found name=sp type=auth:login

If only this one shows up, please check the details of the certificate information within the web.config, as it is most likely including an error.

Also related errors are the following ones - If you see any of these errors within the KanBo Log file, please be sure to check the certificate configuration within your web.config in detail - and also check if the certificate is in the correct certificate store:

Plugins         FATAL | plugin 03470f82-ba88-4247-adb5-6babadd84d47(Sharepoint on-premise authentication): An unexpected exception has occured 
EXCEPTION: System.Exception: Signer of type x509-store encountered an exception (path: /kanbo/(0)plugins/(3)auth.sharepoint/(0)signer)

Security        ERROR | User authentication postback failed (96d9ea3c-e7ae-43d7-bf04-216818055f56):
KanBo.Plugins.Infrastructure.FactoryNotFoundException: Factory not found name=sp type=auth:login

If you will see one of the following errors within your KanBo Log file, please be sure to check to not have more than one Certificate Configurations included in your web.config file - there should be only one, you can use by thumprint or by file, but, not both, as this will cause an error. 

Plugins         FATAL | plugin 03470f82-ba88-4247-adb5-6babadd84d47(Sharepoint on-premise authentication): An unexpected exception has occured 
EXCEPTION: System.Configuration.ConfigurationErrorsException: Multiple elements signer found in /kanbo/(0)plugins/(3)auth.sharepoint

Plugins         FATAL | plugin 03470f82-ba88-4247-adb5-6babadd84d47(Sharepoint on-premise authentication): An unexpected exception has occured 
EXCEPTION: System.Configuration.ConfigurationErrorsException: Multiple elements signer found in /kanbo/(0)plugins/(3)auth.sharepoint

Please find here an example, which you can use, you only would need to change the thumbprint.

Additionally, please check also the expiration date of your High Trust Certificate, you can do this directly within the Certificate Details or also you can follow the instructions in this article here