I am still trying to find a solution to my problem with uploading images. Before upgrading to WP 3.8 I was able to upload images with thumbnails Since I upgraded WP to 3.8. Now I get a generic message of "http error" with nothing to identify what the error is. The image is there, but with no thumbnail in the media library. In the 2013 theme, the image will show up - but larger than I want it. With most other themes, it's not there at all.
I have tried: deactivating all plugins, re-installing WP 3.8, and using the 2013 theme - that didn't help.
And - additional steps taken by my server host:
I'm the server host for EllenGTodd. Some more details: after the upgrade to 3.8, image upload wasn't working at all, as many (not all) upgraders have found. Following a tip elsewhere on this forum I manually edited the database to fix the upload_path (in the options table) — it had gone blank.
After that we could upload photos. But still no thumbnails were generated.
Again following a tip elsewhere in this forum, I looked at the ImageMagick library that PHP uses. These files in the /wp-includes directory:
all had different sizes than the equivalent files in a 3.6.1 install. I moved them aside and copied in the corresponding files from 3.6.1. Result: still no thumbnails (so I restored the 3.8 files).
Can anyone provide further assistance on this? Thank you!