DKIM=temperror

Recently I have checked my messages headers of the mail that comes from the andreybondarenko.com MX and found that Google shows that my DKIM signature is invalid:

Authentication-Results: mx.google.com; dkim=temperror (no key for
 signature) header.i=@andreybondarenko.com;

In the spam score section:

DKIM_SIGNED,T_DKIM_INVALID

However the header itself is present:

DKIM-Filter: OpenDKIM Filter v2.10.3 andreybondrenko.com CE25780BAC
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=andreybondarenko.com; s=default; t=1483634085;
        bh=w00tuUhwty0/5n/YHiopiY3PpnqKT5BLK9l6TkDNUUk=;
        h=Subject:From:Reply-To:To:Date:From;
        b=J5qB5RF9lrOho1wBpLyLi5a6CwIHZK1sugCr2wpwnPKwEg76RFv2/y8xaiwquqftX
         VhTJH9NLJXcPdu8k8/zN/sc8P1RksNR9EvDw6k2YNEKoeMsKMGgyMC4kAAhcT31IgX
         eqnIqWxhVTVdjRqrqzNPn0wuBbGJgO2bwmFcVsy8=

I have found that it’s quite common configuration error of the OpenDKIM, the selector you choose to store key can be chosen randomly, but the TXT record should match /etc/opendkim.conf. In my case:

##  Defines the name of the selector to be used when signing messages.
Selector   default

But the DNS record:

[user@andreybondarenko ~]$ dig TXT mail._domainkey.andreybondarenko.com

;; ANSWER SECTION:
mail._domainkey.andreybondarenko.com. 1800 IN TXT "v=DKIM1\; k=rsa\; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCdGRWtWPPZVIg0fy7Pr0+rsBsoL6Imt1GBE/QRd3X5Izv1iAJFUsOtea
f9TI9EO/YFwoLLahzuoZM1oUU4ED3fHlItEnqXCKQhX8Zripi7gfIO+DRFEhGuQtG6OIuA6+c3ivao7DTPk/IFqY7MG5M3wMvAfV+
eIBf1VjmajSwe3wIDAQAB"

Changing ‘Selector’ to ‘mail’ and restating opendkim (it’s faster then change DNS):

Authentication-Results: mx.google.com; dkim=pass
 header.i=@andreybondarenko.com;

In the spam score section:

DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU