This error occurs when the system extensions for mounting the FUSE volumes are not loaded. MacOS High Sierra 10.13 or later comes with upgraded security that does not allow third-party kernel extensions. To use Filr desktop app extensions, perform the following actions:
Click Open System Preferences.
In the Security & Privacy window, click Allow.
NOTE:
If you are on macOS Big Sur, then a system reboot occurs.
On macOS 11 Big Sur (Intel), you may have to reboot after clicking on Allow.
On macOS 11 Big Sur (Apple M1), no third-party kernel extensions are loaded by default. You have to enable Enable Reduced Security in Recovery mode.
To allow loading of a third-party kernel extension in Apple Silicon, perform the following steps:
On the Mac with Apple silicon, select Apple menu > Shut Down.
Press and hold the power button until the Loading Startup options are displayed.
Click Options, then click Continue.
If requested, enter the password for an administrator account.Mac opens in Recovery mode.
In macOS Recovery, select Utilities > Startup Security Utility.
Select the startup disk you want to use to set the security policy.
If the disk is encrypted with FileVault, click Unlock, enter the password, and then click Unlock.
Click Security Policy.
Set the security level to Reduced security.
Allow the loading of third-party kexts.
A new tab called Prefer is introduced in macOS 11 under System Preferences> General. The default value in the Prefer tab is In full-screen. If the value is changed to Always, the UI issues appear in Filr Client.
For a better UX experience do not change full-screen mode to always.