SFDX push error: Property 'publishBehavior' not valid in version 45.0

Question

I'm trying to push source to a scratch that I've been using for 3 weeks, but suddenly I'm getting an error on all my platform events:

Property 'publishBehavior' not valid in version 45.0

It's calling my attention to the meta files for the platform events. Here's an example:

<?xml version="1.0" encoding="UTF-8"?>
<CustomObject xmlns="http://soap.sforce.com/2006/04/metadata">
    <deploymentStatus>Deployed</deploymentStatus>
    <description>Fires when an incoming SMS is matched with an existing Conversation.</description>
    <eventType>HighVolume</eventType>
    <label>IncomingSms</label>
    <pluralLabel>IncomingSmss</pluralLabel>
    <publishBehavior>PublishImmediately</publishBehavior>
</CustomObject>

I see the <publishBehavior> line that it's referencing, but not sure what to do about it. Is this something new?

Answer 1

Found it here in the Summer 19 release notes.

Summer '19 introduced a new field, <publishBehavior>, providing a new option to publish the event AFTER the commit of whatever process called it (so a trigger on that event could expect to find the changes made). Good idea. Default remains "publishImmediately".

My specific issue was that my scratch org where I created the Platform Events is Summer '10 (v46) but my sfdx-project.json file specified "sourceApiVersion": "45.0" which doesn't know what to do with that property. I updated the json file to 46 and everybody's happy.