The pageType variable is a flag used to designate error pages on your site, such as 404 errors. If this variable contains the string errorPage , it populates the 'Pages Not Found' dimension.
Do not set this variable on non-error pages.
Page Type in Adobe Experience Platform Launch
There is not a dedicated field in Launch to use this variable. Use the custom code editor, following AppMeasurement syntax.
s.pageType in AppMeasurement and Launch custom code editor
The s.pageType variable is a string where the value errorPage is its only valid value. Set this variable to this value on any error page on your site, such as on 404 pages.
s.pageType = "errorPage";
Use an eVar to collect the error code so you can get more information on what specific errors visitors encounter on your site.