Hello Madhu,
Please try having the user clear their browser cache and cookies entirely, or test running the report using an Incognito/Private window, as HTTP 400 errors are typically caused by corrupted session data or oversized browser headers rather than a permission issue. If the error still occurs in Incognito, please check if they can run other HTML reports successfully, and try copying this specific report into their "My Content" folder to see if they can execute it from there. This will help us isolate whether the root cause is a localized browser glitch or a profile-specific issue.
Thank you,
Abbas