opendkim still not working – opendkim-genkey: openssl exited with status %d

opendkim not working – opendkim-genkey: openssl exited with status %d offers no solutions.

The problem:

sudo opendkim-genkey -b 2048 -d example.com -D /etc/opendkim/keys/example.com -s mail -v
opendkim-genkey: generating private key
opendkim-genkey: openssl exited with status %d

If I run as root or use sudo I get the same error. No keys are generated.