I have searched high and low for an answer and spent over 4 hours on this seemingly easy problem. I've tried at least 10 different answers on the web and nothing. I am trying to upload my first picture into the new Wordpress site I am starting. upon Upload I get an "http error" and that's all. This is so frustrating. I'm stunned that WP can't bring back a more expressive error so it can be diagnosed and not just continue trial and error for hours. WP 4.8.2 php 7 iis 6 windows 2008 r2
I was finally offered a link to use the browser uploader. I tried that and got a descriptive error message, approximately this: "Php could not get permission to temporary folder UNKNOWN". Now that's something I can work with. I went to php.ini and found sys_temp_dir which says it will default to the standard temporary directory. So it was not set in my php.ini. I set it to a specific folder for php that I created g:\phptemp and restarted IIS. Immediately no problems. Had Wordpress brought back that error message at 8am this morning I would have saved 4 hours poking and proding and trying and failing. Super frustrating but I'm glad I found the answer and could share it because I NEVER found this answer anywhere else.
Set your memory to 200MB or something to test and then reboot the machine. Try wordpress uploads after that.