SushantRao,ACS Commons Error Page Handler works fine for POSTs as well. If an error occurs, Sling handles the error and passes it off to the ACS Commons Error Page handle, which in turn internally makes a HTTP GET request for the error page defined by the @errorPages property.The problem your runnin...

1) Are these existing assets youre re-processing (they've been through DAM Update Asset once before)?2) If you do not need to extract sub assets at all, you can remove the "Create Sub asset" step from your DAM Update Asset Workflow Model (or create a copy and remove the step, and run that via BWM)Al...

Can you use Acs tools jsp code display [1] to report the line in the compiled JSP that is throwing the error?What version of Aem are you using, and have you changed the 404.jsp overlay at all? (Outside of how the acs commons docs recommend)Also if you can report this to the acs commons GitHub issues...