After performing server maintenance, and installing the K2 blackpearl 4.7 Dec 2019 CU, the K2 reports are no longer functional.
This was caused by a rogue "HTTP Response Header" that was added to the "Workspace" site in IIS. After removing the HTTP Response Header, the reporting worked as expected.
Here are the steps we had to perform, to get the reports working again.
- Open IIS, navigate to, and expand the K2 site node.
- Click on the "Workspace" node.
- In the content pane, under the "IIS" section, select the "HTTP Response Headers" option.
- Delete the HTTP Response Header named "X-Content-Type-Options" (Value: nosniff)
- After deleting the header, you will have to perform an IISReset, and clear the browser cache.
- Opening the K2 reports should now work as expected.
We are not sure how the header got there, but a quick internet search suggests that it might have been added by certain anti-virus installation/updates.
When we looked at a Fiddler trace, we noticed that the reporting data was returned, but it did not display correctly on screen. (The screen was blank) After hitting the refresh button on the blank screen, we saw the following error.
_reportListXMLElement can not be NULL.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Exception: _reportListXMLElement can not be NULL
Source Error: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
[Exception: _reportListXMLElement can not be NULL]
SourceCode.Workspace.OOBReports.ParameterControlTable.CreateControls() + 2689
SourceCode.Workspace.OOBReports.ParameterControlTable.OnPreRender(EventArgs e) +76
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3394
Please see "ErrorOnAllReports.png" for a visual when refreshing the report.
When looking at the browser network trace, we saw that there were MIME type errors in the console window. Please see "BrowserConsoleErrors.png" for a visual on the errors we saw in the browser console window.
It is this error that pointed us towardsIIS, and eventually to the deletion of the "X-Content-Type-Options" HTTP Response Header, that resolved the reporting issue.