A while ago I"ve faced with a problem on VPS - there were no free space! I couldn't login into admin panel installed there. SSH was not working too.
The only thing that was wroking was FTP server which helped me to connect and free some space deleting non used files. After that operation I've finally logged in.
So, be patient to the free space available on your server and have a couple of entrances there.
One of the solution to prevent the situation like this is to have a dummy file which can be deleted in such critical moments to free up the space.

To create a file fileed with random numbers use command:

head -c 1G </dev/urandom >myfile

If you head command didn't recognize G option in size - use bytes:

head -c 1073741824 </dev/urandom >myfile

If head command doesn't recognize -c options use dd command:

dd bs=1024 count=1048576 </dev/urandom >myfile

 

Another case is to create file with openssl program

openssl rand -out myfile "1073741824"

Update previous variant but fill file with base64 symbols

openssl rand -base64 -out myfile "1073741824"
linux
bash