If your sim or lot fails to upload sometimes it can be successful by trying to repackage it again but you MUST give it a different name, if you try and re-upload it with the same name you will most times get the same result. One method I like to use in using a different name is by adding -- to it, for example, if I had a sim called Eve that failed to upload, I will go back to CAS and repackage (share) the sim again, but this time instead of calling her Eve I will call her --Eve-- and then try uploading this one instead. If you try using this method several times, making sure you change the name each time, and if it still fails to upload, then there is likely CC causing it to be blocked and needs to be removed.
If you wish to identify and remove problem CC follow these steps;
Step 1) Go to CAS and select a test sim (I use a premade sim from the sim bin that is a default one, so it definitely has no cc already on it).
Step 2) Put one cc item on your test sim that is the same as you have on your sim that will not upload.
Step 3) Package the test sim and call it test a.
Step 4) Do not quit the game, use the options to open the launcher and upload the test sim.
Step 5) Check your studio to see if the test sim has shown up. If it has you know the cc item is ok. You can delete the test sim from your studio.
Step 6) Go back to CAS and put one more cc item on your test sim that is the same as on your sim that will not upload.
Step 7) Upload it again the same as you did before but this time call it the next letter in the alphabet (eg. test a, test b, test c, etc.).
Step 8) Keep repeating step 5 to step 7 until the test sim does not show up in your studio. When this happens you know that cc item you last put on the test sim is causing the problem and can't be used.
Step 9) Remove that cc item from your test sim and save it to the sim bin.
Step 10) Remove that same cc item from your sim that will not upload and try and upload it.
If your sim still fails to show up in your studio then there is likely more cc items that is causing problems and you'll need to retrieve your test sim from the sim bin and continue doing steps 6 to 10 until you have removed all the problem cc from your sim until it shows up in your studio.
In future when you wish to create a sim with cc, to avoid the disappointment of finishing it just to find out it will not show up in your studio, then having to spend a lot of time trying to sort through large amounts of cc to find the problem cc, I would recommend creating one outfit at a time, package it and do a test upload. If it shows up in your studio continue on to the next outfit then test it again. It is far better to discover problem cc as early as possible and remove it from your sim to save you a lot of time. Just remember that when you do test uploads don't give the sim the name you intend to call it, name it test a etc.