Cannot UnCompress Backups after dist-upgrade

Hope this is the rigth forum!
I am having the strangest of problems with one of the servers today.
After we had a database crash, I checked that we had hosted on the server both database backups (gzipped) and Server backuped (from lastnight).
As mysql was complaining that it could not upgrade, I thought this might be a good time for a distro upgrade (moved from debian 8 to stretch). Upon upgrade, the I did not mind much the old mysql, relying on the backups (2 of them).

The probelm is once the dist was finalized succesfully, none of the gzipped files works :(. As strange as it seems, their timestamps are fine (not altered since one year some of them), but I cannot unzip them.

Typical response:

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

issuing file to get their file types, denotes them simply as data

file bck.al.tar.gz
bck.al.tar.gz: data

Tried gziprecover with no luck!

The strace gunzip file.sql.gz leads me to some references of /etc/ld.so.nohwcap; not sure if this has anything to do at all.

strace gunzip alldatabases06062020.sql.gz
execve("/bin/gunzip", ["gunzip", "alldatabases06062020.sql.gz"], [/* 29 vars */]) = 0
brk(NULL)                               = 0x56429a9d4000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=57364, ...}) = 0
mmap(NULL, 57364, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f8e8843d000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\4\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1689360, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f8e8843b000
mmap(NULL, 3795296, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f8e87e8a000
mprotect(0x7f8e8801f000, 2097152, PROT_NONE) = 0
mmap(0x7f8e8821f000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x195000) = 0x7f8e8821f000
mmap(0x7f8e88225000, 14688, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f8e88225000
close(3)                                = 0
arch_prctl(ARCH_SET_FS, 0x7f8e8843c480) = 0
mprotect(0x7f8e8821f000, 16384, PROT_READ) = 0
mprotect(0x564298faf000, 8192, PROT_READ) = 0
mprotect(0x7f8e8844c000, 4096, PROT_READ) = 0
munmap(0x7f8e8843d000, 57364)           = 0
getpid()                                = 3171
rt_sigaction(SIGCHLD, {sa_handler=0x564298da5ef0, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7f8e87ebd060}, NULL, 8) = 0
geteuid()                               = 0
brk(NULL)                               = 0x56429a9d4000
brk(0x56429a9f5000)                     = 0x56429a9f5000
getppid()                               = 3169
stat("/home/bckDB/bck", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
stat(".", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
open("/bin/gunzip", O_RDONLY)           = 3
fcntl(3, F_DUPFD, 10)                   = 10
close(3)                                = 0
fcntl(10, F_SETFD, FD_CLOEXEC)          = 0
rt_sigaction(SIGINT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGINT, {sa_handler=0x564298da5ef0, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7f8e87ebd060}, NULL, 8) = 0
rt_sigaction(SIGQUIT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGQUIT, {sa_handler=SIG_DFL, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7f8e87ebd060}, NULL, 8) = 0
rt_sigaction(SIGTERM, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=SIG_DFL, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7f8e87ebd060}, NULL, 8) = 0
read(10, "#!/bin/sh\n# Uncompress files.  T"..., 8192) = 2301
execve("/bin/gzip", ["gzip", "-d", "alldatabases06062020.sql.gz"], [/* 29 vars */]) = 0
brk(NULL)                               = 0x5641bfe32000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=57364, ...}) = 0
mmap(NULL, 57364, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f832e5de000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\4\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1689360, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f832e5dc000
mmap(NULL, 3795296, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f832e02b000
mprotect(0x7f832e1c0000, 2097152, PROT_NONE) = 0
mmap(0x7f832e3c0000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x195000) = 0x7f832e3c0000
mmap(0x7f832e3c6000, 14688, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f832e3c6000
close(3)                                = 0
arch_prctl(ARCH_SET_FS, 0x7f832e5dd4c0) = 0
mprotect(0x7f832e3c0000, 16384, PROT_READ) = 0
mprotect(0x5641bec5f000, 4096, PROT_READ) = 0
mprotect(0x7f832e5ed000, 4096, PROT_READ) = 0
munmap(0x7f832e5de000, 57364)           = 0
rt_sigaction(SIGINT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGHUP, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTERM, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGXCPU, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGXFSZ, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGINT, {sa_handler=0x5641bea4c1c0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f832e05e060}, NULL, 8) = 0
rt_sigaction(SIGHUP, {sa_handler=0x5641bea4c1c0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f832e05e060}, NULL, 8) = 0
rt_sigaction(SIGPIPE, {sa_handler=0x5641bea4c1c0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f832e05e060}, NULL, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=0x5641bea4c1c0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f832e05e060}, NULL, 8) = 0
rt_sigaction(SIGXCPU, {sa_handler=0x5641bea4c1c0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f832e05e060}, NULL, 8) = 0
rt_sigaction(SIGXFSZ, {sa_handler=0x5641bea4c1c0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f832e05e060}, NULL, 8) = 0
open("alldatabases06062020.sql.gz", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=219860290, ...}) = 0
read(3, "\320\215\325\331Q%,\261\10\237h\346UO\26\33\210\22\225\234\357\32\340\0v!=\373/t\220\2"..., 32768) = 32768
write(2, "\ngzip: alldatabases06062020.sql."..., 55
gzip: alldatabases06062020.sql.gz: not in gzip format
) = 55
close(3)                                = 0
lseek(0, 0, SEEK_CUR)                   = -1 ESPIPE (Illegal seek)
close(0)                                = 0
close(1)                                = 0
close(2)                                = 0
exit_group(1)                           = ?
+++ exited with 1 +++

I even tried the support of Virtualmin, which is rightfully for the paying customers and no other paying support is foreseen.
Has anyone faced a similar issue? Any hints on a desperate hour?

As strange as it is, only .gz and .sql files are affected; all the other files on the system behave normally.

Also transferring to other servers and attempting uncompress yields the same issue! :frowning:
Strange because some (very old backup files) are the ones that has been used to restore to this server.

Is it possible you transferred these backups using FTP in text mode? In particular, if you were on a Windows box it may have tried to translate line feeds which will corrupt the file.

it is the same for transferred files or for files on the same server thah have not been transferred.

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