Error: No PyUSB backend detected

[jsatk]

I only use YubiKeys for GPG. Since OTP via YubiKey isn't supported in Firefox or Safari as of this writing I don't use it. Unfortunately when I attempt to disable OTP via USB it throws this error.

$ ykman config usb --disable OTC
Usage: ykman [OPTIONS] COMMAND [ARGS]...

Error: No PyUSB backend detected!

Also when I inquire about the version I get this warning:

$ ykman -v
YubiKey Manager (ykman) version: 1.0.1
Libraries:
    libykpers not found!
    <pyusb backend missing>

I've done an install and reinstall of both ykman and ykpers.

I've tried searching for a resolution to this but to no avail. Any help on disabling OTC for this Yubikey 4 nano would be greatly appreciated.

[dagheyman]

How did you install ykman?

libykpers not found!
<pyusb backend missing>

indicates that the c-libraries are not available. See the installation instructions. If you are using macOS for example, I'd recommend $ brew install ykman.

[dagheyman]

Any help on disabling OTC for this Yubikey 4 nano would be greatly appreciated.

The correct command, once ykman is installed, would be
$ ykman mode CCID+FIDO

[dagheyman]

Any other issues, please contact Yubico Support.

[jsatk]

That's how in installed it – homebrew.

…

On 12/10, Dag Heyman wrote: How did you install ykman? ``` libykpers not found! <pyusb backend missing> ``` indicates that the c-libraries are not available. See the installation [instructions](https://github.com/Yubico/yubikey-manager#installation). If you are using macOS for example, I'd recommend `$ brew install ykman`. -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #185 (comment)

[jsatk]

@dagheyman I don't understand why this issue is closed.

When brew install ykman and then run ykman info it throws the error I posted above.

[jsatk]

[dagheyman]

Now it seems to find libykpers at least.

Could you try $ brew reinstall libusb ?

[jsatk]

That did it @dagheyman. No idea what the issue was or why it got b0rked. Odd.

Thank you so much.

[jsatk]

Resolution is to reinstall libusb via brew reinstall libusb.