Cannot boot a VPS with Ubuntu 18.04 init exist but couldn't execute it

i'm trying to repair my virtual server which after a reboot prints the following lines and doesn't start, it seem to be a problem with /etc/init but can't solve it:

[    3.226615] md: ... autorun DONE.
[    3.336670] EXT4-fs (sda): mounted filesystem with ordered data mode. Opts: )
[    3.338548] VFS: Mounted root (ext4 filesystem) readonly on device 8:0.
[    3.449102] devtmpfs: mounted
[    3.452100] Freeing unused decrypted memory: 2036K
[    3.454042] Freeing unused kernel image (initmem) memory: 2204K
[    3.455503] Write protecting the kernel read-only data: 32768k
[    3.458050] Freeing unused kernel image (text/rodata gap) memory: 2028K
[    3.460497] Freeing unused kernel image (rodata/data gap) memory: 196K
[    3.505976] x86/mm: Checked W+X mappings: passed, no W+X pages found.
[    3.508027] rodata_test: all tests were successful 
[    3.509863] Run /sbin/init as init process 
[    3.682677] Run /etc/init as init process 
[    3.852167] Starting init: /etc/init exists but couldn't execute it (error -) 
[    3.854890] Run /bin/init as init process [    4.024199] Run /bin/sh as init process 
[    4.192354] Starting init: /bin/sh exists but couldn't execute it (error -13) 
[    4.194356] Kernel panic - not syncing: No working init found.  Try passing . 
[    4.197811] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.10.2-x86_64-linode141 
[    4.199581] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14 
[    4.201985] Call Trace: 
[    4.203418]  dump_stack+0x6d/0x88 
[    4.204677]  ? memcpy_orig+0xd0/0x10f 
[    4.205955]  panic+0x101/0x2d7 
[    4.207072]  ? rest_init+0xae/0xae 
[    4.208218]  kernel_init+0x106/0x112 
[    4.209465]  ret_from_fork+0x22/0x30 
[    4.210722] Kernel Offset: 0x1c00000 from 0xffffffff81000000 (relocation ran) 
[    4.213177] ---[ end Kernel panic - not syncing: No working init found.  Try- 

Does anyone know how can i solve it or what could be the problem?

Thanks in advance!