client: keybase login fails although gpg and private key are installed

When I try to login I get the follwoing Error and advice:

ERROR in Login

Sorry, your account is already established with a PGP public key, but this
utility cannot access the corresponding private key. You need to prove
you're you. We suggest one of the following:

  - install GPG and put your PGP private key on this machine and try again
  - reset your account and start fresh: https://keybase.io/#account-reset

I have gpg installed and the private key to my keybase.io key is also available in my local keychain. Is there any way to debug how you try to call gpg and what gpgs error message is?

gpg --list-secret-keys --fingerprint  dirkjaeckel
gpg: Note: signatures using the MD5 algorithm are rejected
sec   4096R/A53E4591 2015-04-01 [expires: 2018-02-03]
      Key fingerprint = 1C66 76AF 8572 DDE3 623B  7880 A258 970F A53E 4591
uid                  Dirk Jäckel <dirk@jaeckel.com>
uid                  Dirk Jäckel <dirkjaeckel@keybase.io>
ssb   4096R/BE3132A7 2015-04-01 [expires: 2018-02-03]

my log id: 24473b09e780b96c2f43761c