Comment 21 for bug 1873506

I am also having the same "Invalid argument" error with 'ubuntu/focal64' version '20210803.0.0' when doing vagrant up.
Manually running the mount command from inside the guest machine brings the same error.
The host machine (also Ubuntu focal64) is running vagrant 2.2.18 and Virtualbox 6.1.22
I did note in the guest machine dmesg (see below), that it shows version 6.1.16_Ubuntu for vboxsf but VBoxService is version 6.1.22_Ubuntu. I

Output from vagrant up:

Mounting shared folders...
/vagrant => /home/xx/checkout
Vagrant was unable to mount VirtualBox shared folders. This is usually
because the filesystem "vboxsf" is not available. This filesystem is
made available via the VirtualBox Guest Additions and kernel module.
Please verify that these guest additions are properly installed in the
guest. This is not a bug in Vagrant and is usually caused by a faulty
Vagrant box. For context, the command attempted was:

mount -t vboxsf -o uid=1000,gid=1000,_netdev vagrant /vagrant

The error output from the command was:

/sbin/mount.vboxsf: mounting failed with the error: Invalid argument

dmesg output:
[ 9.581826] vboxsf: g_fHostFeatures=0x8000000f g_fSfFeatures=0x1 g_uSfLastFunction=29
[ 9.581876] vboxsf: Successfully loaded version 6.1.16_Ubuntu
[ 9.581890] vboxsf: Successfully loaded version 6.1.16_Ubuntu on 5.4.0-80-generic SMP mod_unload modversions (LINUX_VERSION_CODE=0x5047c)
[ 9.624089] 23:59:13.455579 main VBoxService 6.1.22_Ubuntu r144080 (verbosity: 0) linux.amd64 (Jun 22 2021 07:15:58) release log
               23:59:13.455582 main Log opened 2021-08-07T23:59:13.455569000Z
[ 9.624130] 23:59:13.455666 main OS Product: Linux
[ 9.624149] 23:59:13.455687 main OS Release: 5.4.0-80-generic
[ 9.624163] 23:59:13.455705 main OS Version: #90-Ubuntu SMP Fri Jul 9 22:49:44 UTC 2021
[ 9.624185] 23:59:13.455719 main Executable: /usr/sbin/VBoxService
               23:59:13.455719 main Process ID: 679
               23:59:13.455720 main Package type: LINUX_64BITS_GENERIC (OSE)
[ 9.628306] 23:59:13.459819 main 6.1.22_Ubuntu r144080 started. Verbose level = 0
[ 9.630916] 23:59:13.462430 main vbglR3GuestCtrlDetectPeekGetCancelSupport: Supported (#1)
[ 16.847539] vboxsf: Invalid info signature: 0x75 0x69 0x64 0x3d!
[ 16.847543] vbsf_read_super_aux err=-22
[ 16.939693] vboxsf: Invalid info signature: 0x75 0x69 0x64 0x3d!
[ 16.939697] vbsf_read_super_aux err=-22
[ 22.079670] vboxsf: Invalid info signature: 0x75 0x69 0x64 0x3d!
[ 22.079674] vbsf_read_super_aux err=-22
[ 27.219309] vboxsf: Invalid info signature: 0x75 0x69 0x64 0x3d!
[ 27.219313] vbsf_read_super_aux err=-22