Exim TLS error while reading file literally means it really can not read the [certificate] file.

As part of our Server Management Services, we assist our customers with several Exim queries.

Today let us see how we can fix the TLS error in Exim.

Exim TLS error while reading file

Generally, the exim4 certificate and key files need to have the owner and mode set in a strict way. Otherwise, Exim will not read it.,

Instead, while we are in the cert/key setup phase it will give us this error.

The exact owner and mode are:

root@hostname:/etc/exim4# ls -l exim.crt exim.key
-rw-r----- 1 root Debian-exim 2224 mag 30 17:13 exim.crt
-rw-r----- 1 root Debian-exim 1704 mag 30 17:12 exim.key

Moving ahead, let us see how our Support Techs fix this error for our customers.

By default exim4 looks for CONFIGDIR/exim.crt and CONFIGDIR/exim.key (CONFIGDIR is for the /etc/exim4)

So, we copy the certificate and key to these two file names.

In addition, we need to remove all of the configuration entries we previously added. This is for exim4 to look for the default entries without any distraction.

After that, we need to ensure that the certificate and key are readable by exim4.

To do so, our Support Techs follow the steps below:

1. First, we set the group to Debian-exim (chrgrp Debian-exim exim.*)
2. Then we set the group read permission on (chmod g+r exim.*)
3. Finally, we restart the exim4

Once done, we use checktls.com to ensure the TLS and certificate are working correctly.

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Conclusion

In short, we saw how our Support Techs fix the Exim error for our customers.