Serial number is invalid why

If you go to Settings > General > About on your iPhone does it list a "Serial Number" made up of 12 letters/numbers? Or does it have something like all 0's or blank?

If it lists a real-looking serial number try typing that into the website:

http://checkcoverage.apple.com

Does that website confirm it is a specific model of iPhone, or does it say it is invalid there?

If it says the serial number is invalid on that website, then there is a problem and you may have to contact Apple support or bring it in for service. If this iPhone was deactivated because it was an insurance/return, stolen, etc., it will not be able to be fixed.

For example, if this is a used iPhone it may have a de-activated serial number if it was replaced under warranty, or if it was replaced by your carrier/insurance.

Without a valid/active serial number you will not be able to use the App Store and many Apple services.

Hopefully your failed upload has not disabled the phone, and you will be able to go into Settings/About to read the serial number of the device. Then enter the serial number in https://checkcoverage.apple.com/ and see what it tells you.

We need more information about your issue. What are you trying to do and where do you see this message?