After an aptitude update on dovecot to version
Error: Failed to initialize SSL server context: Couldn't parse DH parameters: error:0906D06C:PEM routines:PEM_read_bio:no start line: Expecting: DH PARAMETERS: user=<>
Of course first, we checked for the Diffie-Hellman parameters file that was there, and had the appropriate permissions.
The solution to this problem was to change the line
ssl_dh = /etc/dovecot/dh.pem
Afterwards dovecot is able to re-access the Diffie-Hellman Params file and works without any issues.
If you’ve not yet created you DH Params file you can use the following command to create it. Please keep in mind that creating a 4096 DH file could take some time 😉 – you can use 2048 with little less security instead
openssl dhparam -out /etc/dovecot/dh.pem 4096
Further information regarding the DOVECOT SSL settings can be found here: