gpg-agent problem ERR 67108949 No Pinentry

[wipro]

Hi,

I am using Thunderbird & enigmail (1.9.3) on a Linux Mint 17.3 system. I
want gpg-agent to store the passphrases of my keys but I am stuck now
after going through all the enigmail debug advice and exhausting the
knowledge available on the enigmail forum.

My environment:
- Linux Mint 17.3 KDE
- gpg2 and gpg-agent version 2.0.22
- Kgpg and gpa frontends
- Thunderbird 52.4.0, enigmail 1.9.3

The gpg-agent ist started from
/usr/share/upstart/sessions/gpg-agent.conf at login

I have "use-agent" in my ~/.gnupg/gpg.conf.
I have "pinentry-program /usr/bin/pinentry" in my ~/.gnupg/gpg-agent.conf

Still enigmail is throwing an error, that pinenrty could not be opened
and in the attached log file gpg-agent_autostart-17102017_NOK.log there
is three times this "ERR 67108949 No Pinentry".

Now the strange part: If I start gpg-agent manually from a terminal
everything works fine: decrypting an email is possible and the gpg-agent
log confirms that (see attached log file gpg-agent_manual_OK.log).

commands in a terminal:
killall gpg-agent
gpg-agent --debug-level expert --use-standard-socket --daemon /bin/sh

Any ideas what could be wrong in the gpg setup?
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