I was working through the Getting Started with Salesforce DX module on trailhead and when it came time to push the Dreamhouse app up to my scratch org I got a dozen or so error messages complaining about all sorts of things.

PROJECT PATH                                                                                    ERROR
──────────────────────────────────────────────────────────────────────────────────────────────  ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
force-app/main/default/objects/Property__c/Property__c.object-meta.xml                          Can't specify an external sharing model for Property__c
force-app/main/default/objects/Favorite__c/fields/Property__c.field-meta.xml                    referenceTo value of 'Property__c' does not resolve to a valid sObject type (65:13)
force-app/main/default/objects/Favorite__c/listViews/All.listView-meta.xml                      In field: columns - no CustomField named Favorite__c.Property__c found (88:16)
force-app/main/default/layouts/Broker__c-Broker Layout.layout-meta.xml                          In field: relatedList - no CustomField named Property__c.Broker__c found (81:19)
force-app/main/default/layouts/Favorite__c-Favorite Layout.layout-meta.xml                      In field: field - no CustomField named Favorite__c.Property__c found (13:26)

Luckily the error messages are pretty useful. In this case it looks like the “External Sharing Model” was not turned on in my scratch org. This appears to be turned off by default.

In order to get this step to work:

1. 1. Log into your scratch org sfdx force:org:open
   2. Go to Setup
   3. In the Quick Search box look for Sharing Settings
   4. Click on Enable External Sharing Model 

Now you can run the push command and deploy the Dreamhouse app without any issues.

Keep on trailbalazing!