Chrome OS no longer able to manually import Root CA Certificate

tomrgsd ,

You've mention that it only impacts after upgrading Chrome OS, please confirm at that time SFOS is from same version. If it is true then chances are high that it is due to Chrome OS.

Can you provide that CRT file so we can confirm? Because Chrome OS does not support DER format certificate.

The format is a .crt file. This used to work and was our default process for devices not part of our Google assets. We could manually import the certificate authority and it would allow it. Now it says, for the same file we've used for years and is still valid, file type not supported. I never thought it was Sophos causing the issue. I'm almost certain it is a Google change that is causing it. I was looking to see if anyone else was having the issue and if possibly there was fix or workaround. I can still assign the .crt file to be pushed out to managed devices and it works, just can't do it locally on the ChromeOS device.

Just in case ChromeOS is somehow being weirdly strict about things...

The CRT file should be in PEM format, not DER.
It should start with
---- BEGIN CERTIFICATE----
and end with
-----END CERTIFICATE-----

Trim any blank lines...  maybe save in CR versus CRLF line ending formats.  Any import should not care but who knows...
support.google.com/.../3505249

tomrgsd 

You can use below command to convert certificate in PEM file

openssl x509 -in <certificate file path> -inform der -outform pem -out <output certificate file path>

Then try to import that PEM formated file.