STARTTLS=server, error

[AN]

13.0-CURRENT FreeBSD 13.0-CURRENT #0 r366444: Mon Oct  5 18:14:47 EDT 2020
amd64 1300119

If anyone could provide advice on how to fix the following issue it would
be appreciated.  Also if you have a pointer to relevent docs.

from sendmail log:
Oct  5 20:09:17 mail sm-mta[853]: STARTTLS=server, error:
PEM_read_bio_X509_CRL(/etc/mail/certs/revoke.crl)=failed


# ls -l /etc/mail/certs
total 9076
-rw-r--r--  1 root  wheel     1302 Jul  2  2018 cacert.pem
-rw-r--r--  1 root  wheel      769 May 14  2019 dh.param
lrwxr-xr-x  1 root  wheel       10 Jul  2  2018 f37a271f.0 -> cacert.pem
-rw-r--r--  1 root  wheel     1346 Jul  2  2018 host.cert
-rw-------  1 root  wheel     1704 Jul  2  2018 host.key
-rw-r--r--  1 root  wheel  9220074 May 14 18:26 revoke.crl
drwxr-xr-x  2 root  wheel      512 May 14 17:25 test_cert

Thanks in advance.