The error messages are reporting that there is no space left on the device for writing the files /usr/lib/locale/ig_NG/LC_COLLATE and /usr/lib/locale/ig_NG/LC_ADDRESS
I suspect the filenames are misleading and it has actually failed to download the image due to running out of space. Depending on how you have your server set up, you may be able to clear space somewhere or may need to look into increasing storage capacity.
If you’ve run out of space purely because of uploads on your Discourse forum, it may be worth looking into migrating uploads to S3 (whether that’s Amazon S3 or an alternative) storage. You will probably still need to upgrade the storage temporarily if you do want to go that route though.