Attach documents in Problem Report through REST Service

Hello,

I want to upload an attachment to a Problem Report through REST Service and I am following the steps provided in the below link

https://support.ptc.com/help/windchill_rest_services/r2.4/en/index.html#page/windchill_rest_services/example_changemgmt_upload_attachmt_changeissue.html

But I am facing an issue while carrying out the stage 2 step, when executed it says, "The system is unable to process your request at this time. Please try again later. If the problem persists contact your system administrator.". Requesting you to shed some light on this issue.

Thanks,

Sha