[Milhouse]

I reduced the amount of movies to 9 movies and tried again. of 107 to cache it starts throwing errors again at number 45. so both were just a little over half.

Remote artwork sucks. How many times do I have to repeat this...

Kodi is performing the download and not the script, so it's a problem between Kodi and the remote website.

It may be the remote website is imposing some sort of rate limiting. Or the artwork no longer exists. Or the remote website is having a bad day.

If you look at the log you'll see the encoded urls that are being processed - an example from your log is:

text:
2018-04-23 21:43:40.853523:Thread-1  : preparedl.JSON WEB REQUEST: [POST] [{"method": "Files.PrepareDownload", "params": {"path": "image://https%3a%2f%2fassets.fanart.tv%2ffanart%2fmovies%2f23398%2fmoviebanner%2falvin-and-the-chipmunks-the-squeakquel-53f60665859d9.jpg/"}, "jsonrpc": "2.0", "id": "preparedl"}]

The decoded url is:

text:
https://assets.fanart.tv/fanart/movies/2...5859d9.jpg

Loading this url in a browser results in the error:

text:
{ "status": "error", "error message": "Not found" }

(I also had a "500 Internal Server Error")

So either the artwork no longer exists (gone forever) or fanart.tv is having a bad day. If the latter, which seems likely, maybe the artwork will be accessible later, or tomorrow. If the former you'll need to fix your media library and associate new artwork that does exist.

If you want to avoid this sort of problem in future you should use only local artwork. I've written the mklocal.py script which you can use to convert your remote artwork into local artwork, and it will remove from your library any remote artwork that no longer exists (allowing you to use something like the Artwork Beef add-on to re-associate new artwork) or you can manually download the artwork you prefer and re-run mklocal.py and it will associate your movies/tvshows with that artwork.