When using the Challenge/Response mode with a Yubikey, if you unplug the key and replug it, the key is no longer detected or able to do the challenge / response authentication.

This leads to being unable to save the database after any changes.

Error message states:
Writing the database failed. Unable to issue challenge-response.

Expected Behavior

Key should be redetected on replug - or only accessed when the functionality is needed.

Current Behavior

1. Open a challenge / response secured database
2. Remove the yubikey
3. Make a change to something
4. Plug in the Yubikey
5. Try to save the database.

Possible Solution

Should only access the Yubikey when a challenge is required. Once the challenge is complete, the key should be released.

Debug Info

KeePassXC - Version 2.2.0
Revision: caa49a8

Libraries:

• Qt 5.7.1
• libgcrypt 1.7.7

Operating system: Fedora 26 (Twenty Six)
CPU architecture: x86_64
Kernel: linux 4.11.6-301.fc26.x86_64

Enabled extensions:

• KeePassHTTP
• Auto-Type
• YubiKey