Why does gpg key pair generation fail with error message "/usr/bin/pinentry: line 22: xprop: command not found" ?

Issue

• Trying to generate keys and the process fails, see below:

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You need a Passphrase to protect your secret key.

can't connect to `/home/test/.gnupg/S.gpg-agent': Connection refused
/usr/bin/pinentry: line 22: xprop: command not found
Please install pinentry-gui
gpg-agent[30566]: can't connect server: ec=4.16383
gpg-agent[30566]: can't connect to the PIN entry module: End of file
gpg-agent[30566]: command get_passphrase failed: No pinentry
gpg: problem with the agent: No pinentry
gpg: Key generation canceled.