We have upgraded our application from Pega 6.2 to Pega 7.3 and getting exception in logs as - "sax parse error: Content is not allowed in prolog"
Its happening mainly in an input screen which is having "Multiple tabs". Each tab having different fields/controls and Refresh sections event based on conditions. Issue is intermittent but it happens primarily when -
1. Data is being captured in one of the tab and on any action event of a control when section gets refreshed, we get the exception in logs.
2. From one tab, when we jump to any other tab randomly, in screen we get - "Stack Trace Error message - Failed to find instance @baseclass.PerformTabbedAgreement of type Rule-HTML-Harness." and logs gives us error - "sax parse error: Content is not allowed in prolog"
The Harness rule is already present in application Work class