How do I update Drupal 8.2.3 REST configurations for an entity? According to the documentation, I need to update the REST configuration for each entity type. RESTUI seems not to work with 8.2.3, so I figure I'm supposed to update this by hand, for example in rest.resource.entity.node.yml.

I do that, and then I'm stuck. Where does this file go? Does it go in my code somewhere? Am I supposed to import it through Configuration Synchronization (admin/config/development/configuration/single/import)? 

I did try to import using Config Synch, but I got the following error, which means nothing to a newbie like me: An entity with this machine name already exists but the import did not specify a UUID. 



Sorry if this is already documented somewhere, but I can't find an explanation anywhere for how to update these settings, and they seem pretty important for using the REST services. I'm currently using the Features Module as a workaround but it's kind of an ugly approach for something that seems like it should be simple.

Thanks in advance!
To answer your second question, you'll want to remove the imported configuration from the database and then reimport it with an included UUID - after which you can overwrite the config by re-importing it as many times as you like.

But first, when you upload a config, you should give it a more meaningful ID; rather than 'entity.node', you want something like 'my_config_for_this_thing'.

So in steps:


In your DB, find the config you uploaded (and see note about about the config ID):

select name from config where name like '%entity.node%';

Copy the full name that matches your config.  It will be something like 'migrate_plus.migration.entity.node'.
Delete that row from the database

delete from config where name = '*paste that name here*';

In your yml file, include a uuid. You can generate one locally or using a web tool such as https://www.uuidgenerator.net.  This will look something like

id: some_meaningful_identifier
label: 'A label to describe my config'
status: true
uuid: ac1d69cc-382f-49d2-921e-bb0673fd62ea

Clear your Drupal cache
Then re-import and you should be in better shape.