Good afternoon @shivadeveloper878,
Thank you for contacting Octopus Support and sorry to hear you are having issues with one of your package pushes to Octopus. There is another forum post similar to this where a user was getting the same error as you.
I am wondering if you can check over that forum post and see if your error logs are showing similar results (ie are the logs telling you the package file is not found).
If so there may be some suggestions in that post you can try. Let me know if you are getting similar errors and if you are able to look at your build logs to see if the package has been pushed to Octopus and it is in the correct location.
I look forward to hearing from you,
Kind Regards,
Clare