Problem: When I try to install a plugin at WordPress, I hit an error:
Installation failed: Download failed. Destination directory for file streaming does not exist or is not writable.
This is due to some permission problem when the content folder. I was editing some files as a sudo su power user, but the install requires a ec2-user write acesss.
Solution: Assuming you are setting up on AWS EC2 instances as a ec-user and the WordPress is inside /var/www path, then run the command:
sudo chown -R ec2-user:apache /var/www
After changing the ownership, you should be able to install the plugin now.