Q:

Unable to install CA certificate on Android Oreo

I am trying to install a certificate on Oreo version of Android. I have downloaded the certificate on internal storage and the format is .cer and pin is set for lock screen.
I have tried following steps:

Settings-- Security & Lockscreen-- Credential storage-- Install from
  storage--

I can see the cert file but it is greyed out and there is no option to select it.
Is there any way to do it?

A:

Had the same problem here - Certificates in the download directory were all greyed out.
Pretty sure it's a bug - here's the workaround that worked for me. 
I was navigating to the file via the Download shortcut in the Open from sidebar. Instead, don't use the shortcut. From the Open from sidebar, select the base phone storage (labelled as your phone name) and navigate to your Downloads directory manually. Now, my certs can be selected.

