Sometimes when we have issues with backend application server but SPS still displays error message below.
Is there a way to configure SPS redirect to "errorwithapplication1.html" when there is an issue with backend application1?
You probably be able to achieve this by setting SPSErrorMessages.properties and WebServerErrorMessages.propertiesfiles on SPS :
You might check also for errors occuring at the SPS Agent level :
Hope that helps,
Adding to Patrick's update, Kindly refer below Kb article as well.