Input/Output error most often means that the underlying storage has a problem (e.g. broken disk). check the syslog/journal for clues what happened
Thank you very much for your answer, in the syslog it shows me permission error, or that is what I interpret. I'm leaving it in case someone can help me.
Thanks.
Oct 01 00:01:01 sktcsv1 systemd[1]: Started Proxmox VE replication runner.
Oct 01 00:01:09 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:09 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:09 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:09 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:09 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:09 sktcsv1 pvestatd[1721]: mkdir /media/template: Input/output error at /usr/share/perl5/PVE/Storage/Plugin.pm line 1039.
Oct 01 00:01:19 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:19 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:19 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:19 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0
Oct 01 00:01:19 sktcsv1 kernel: EXT4-fs error (device sdc1): __ext4_find_entry:1531: inode #2: comm pvestatd: reading directory lblock 0