Check out Kinggath Creations on Youtube. He has some pointers for uploading to Bethesda and packing BA2 archives for FO4 that are more or less applicable in his tutorial videos. Bethesda Mod School playlist. Pretty handy overall.

Otherwise no, I have never tried uploading to creations before, so I can't really say what is happening other than it sounds like it's failing to create the esm properly.

Also, I stopped using Starfield CK because it has issues that are just painful to deal with at times, and I felt like working with Fallout 4 was just the better bet until they fix it. Not that you can't do stuff with it, and I have, but I just find the amount of issues overwhelm my desire to work with it right now.

Are you saving the ESP first? The steps I take are to open CK, save the ESP I am going to make - then load all needed ESMs plus setting my ESP as the active file. Do my modifications/build the mod, then SAVE and then convert to ESM, save again, and then upload to Bethesda

If your esp file is 0kb there is nothing in it. What are you trying to make, and do you have a complete esp with content? I have had a few crashes that also wipe the esp, so maybe that happened to you. Check your backups and see if you have one with data in it.

Originally posted by Sadyr:

If your esp file is 0kb there is nothing in it. What are you trying to make, and do you have a complete esp with content? I have had a few crashes that also wipe the esp, so maybe that happened to you. Check your backups and see if you have one with data in it.

Sadyr is correct. If your ESP is 0kb, your ESM will be 0kb. The default assumption is that your ESP has no actual content. CK doesn't think you've changed or added anything. This can happen if you did not set your ESP as ACTIVE when loading it. Checking the little box beside the ESP name is not enough. It will not save changes to the ESP if it isn't the ACTIVE esp. So, make sure you are clicking the button bottom left to make it the Active file before loading it into CK. Then your changes should save to the ESP just fine, and converting to ESM should work.

Im curious, are you storing the game and creation kit on a secondary drive? Im having the same problem (though only on my work laptop where the game is on the D:/ drive, my personal desktop has no issue saving .esps as .esms)