"Invalid or corrupt jarfile."

[AlexK5]

Hi. I'm experiencing a problem which I've seen before from many other people. I tried searching the problem and researching it but couldn't find any answers to help fix it. So the issue is I'm trying to host a tekkit server. This issue occurs with every technic pack server I've tried. I click the run.bat server and the command prompt opens up and says this:

C:\Users\Boba-Fett\Downloads\Moonquest Server>java -Xmx3000 -jar minecraft_server.jar -o true

Error: Invalid or corrupt jarfile minecraft_server.jar

C:\Users\Boba-Fett\Downloads\Moonquest Server>PAUSE

Press any key to continue . . .

Now, moonquest is a downloaded pack, but it still does this same problem with every other default modpack, I just used this one as an example. I could really use some help!