The uploaded file could not be moved to wp-content/uploads

Provided that your wordpress directory is "owned" by the correct user, you should see your problem resolved if you set the permissions to 755.

Log on to your server, and cd to wp-content, then run:

chmod 755 uploads

It is most likely a permissions issue. Find the user processes running on the site by navigating to your sites wp-content folder on the server your site is on. Then type this;

ps aux | egrep '(apache|httpd)'

Ignore root, but look at the other users

root      2507  0.0  0.3 423820 14328 ?        Ss   Aug04   0:51 /usr/sbin/httpd
apache    4653  0.5  1.9 483900 77252 ?        S    16:27   0:14 /usr/sbin/httpd
apache    4654  0.5  2.1 500160 84912 ?        S    16:27   0:13 /usr/sbin/httpd
apache    4656  0.8  2.0 484708 78712 ?        S    16:27   0:21 /usr/sbin/httpd
...

For me it actually was apache (usually www-data). Finally change the users of the uploads folder to this user;

sudo chown -R apache:apache uploads

(make sure you are in the directory above the uploads folder when running this command)

This will permit the correct user to access this directory using the correct access permissions of 755.

By using the dreadful '777' advice of others, you are simply allowing the correct user to access the directory assigned to the incorrect user - as well as anyone else who can access that directory!

For anyone who has landed here but using a Windows / IIS platform then you can achieve the same thing by giving modify permissions to the Everyone group for your wp-content\uploads directory.

I would recommend, for security's sake, instead of

sudo chmod 777 uploads

which gives permissions (read, write, execute) to the user who owns the folder (the root), to other users in the file's Group and to other users not in the file's group (anyone else).

sudo chmod 755 uploads

which gives all permissions to the owner, but only read and execute permissions to the other users