Unable to create directory in wp-content/uploads in Wordpress
Debian like:
chown -R www-data:www-data /var/www/{yourpath}/wp-content/uploads
I was having a similar problem after migrating from a development site to a production site. It turned out that the message is deceptive. Check Settings, Media. Verify the directory for media is accurate for the current site. If the site was migrated, the directory listed still be from the old site and may need to be updated.
If this error is showed after migrating wordpress to new server check upload path in:settings->media->Store uploads in this folder
default value is wp-content/uploads.
Probably you have old path.