login page - Authentication Error

Hello, today I tried to log into the control panel, but I can’t do it. I enter my username and password, but instead of logging in, it keeps redirecting me back to the login page. What should I do?

I resolved the issue by deleting the backups. For some reason, they were not working correctly since Friday and filled up all the disk space. How can I determine what caused this?

root@example:~# df -h
Filesystem Size Used Avail Use% Mounted on
tmpfs 5.9G 41M 5.9G 1% /run
/dev/sda3 1.6T 1.5T 0 100% /
tmpfs 30G 1.2M 30G 1% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
/dev/sda2 2.0G 166M 1.7G 9% /boot
tmpfs 5.9G 0 5.9G 0% /run/user/0
root@example:~# df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
tmpfs 7715848 689 7715159 1% /run
/dev/sda3 104726528 366937 104359591 1% /
tmpfs 7715848 2 7715846 1% /dev/shm
tmpfs 7715848 2 7715846 1% /run/lock
/dev/sda2 131072 324 130748 1% /boot
tmpfs 1543169 19 1543150 1% /run/user/0

Check the number of packages it create …

And debug if it is running properly by running it manually