Hi. It sounds like you're looking for a way to set registered protocol handlers via master_preferences. If this is correct, can you use the RegisteredProtocolHandlers policy setting (https://www.chromium.org/administrators/policy-list-3#RegisteredProtocolHandlers) to accomplish your goals? If not, could you be a little more specific regarding what you're trying to accomplish? Thanks.

We have an application that uses custom scheme, whenever chrome launches it, it prompts user whether to run it or not. 

The user has to select "Always open these types of links in the associated app" for the application to work, but in practice users ignore it causing the application to fail. 

We have a logon script to modify Preference file
"C:\Users\<username>\AppData\Local\Google\Chrome\User Data\Default\Preferences"

by adding our custome scheme ("alert":false) in excluded_schemes

"protocol_handler":{"excluded_schemes":{"alert":false}}


This works but it is not ideal. We are hoping to find a more elegant solution i.e. Group Policy settings that adds excluded_schemes for user appdata or Master Preferences. 


  

Thanks for the clarification. I'm not sure why this isn't working for you. With this master_preferences file:

{"protocol_handler":{"excluded_schemes":{"alert":false}}}

I see that setting present in User Data\Default\Preferences for new Chrome users.

As for better ways to control this, I'll defer to benwells@. Ben: is there another way for administrators to suppress this prompt for specific protocols? If not, does it make sense to introduce a new policy setting for this? Thanks.

I'd say there isn't a better way to do this. This recently (like ... 12 months ago. Recent in chrome history) changed from being stored in local state to being a pref.

I think it does make sense to introduce a new policy setting for this, but I don't think it would be anyone in my team doing it. Putting back to available.

OP: could you provide the master_preferences file that you're using? Perhaps there's a formatting error in it that prevents it from working.