here is an additional thing that may help you.
I was using a brand new Salesforce Production Instance build on Spring 17.
When I started the deployment into Production instance, I bumped into the above error.
ChatterAnswersEscalationTriggerTest line 17, column 13: No such column
'CommunityId' on entity 'Case'. If you are attempting to use a custom
field, be sure to append the '__c' after the custom field name. Please
reference your WSDL or the describe call for the appropriate names.
Stack Trace: null
chatter_answers_question_escalation_to_case_trigger: trigger body is
invalid and failed recompilation: Entity is not org-accessible Stack
Trace: null
As I had done during my Sandbox deployment, I uploaded the package to delete the Trigger and Apex Class that caused these 2 issues.
With very little trouble I deployed it into Sandbox as it did not demand me the code coverage.
When I did the same in Prod, as these where Apex Deployment, it required me to have a code Coverage of 75% instead of 0%.
In order to get around the problem, not sure if that is the best option, I wrote a dummy Apex Class and a supporting test class, had few method built up with around 300 lines of code that was covered on running the test class.
Once tested in Sandbox, I deployed the same in Production and bingo it worked like a charm.
here is the update package.xml where InitialCodeCoverage and InitialCodeCoverage_UT are the dummy apex classes I wrote for code coverage.
<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<members>ChatterAnswersEscalationTriggerTest</members>
<members>InitialCodeCoverage</members>
<members>InitialCodeCoverage_UT</members>
<name>ApexClass</name>
</types>
<types> <members>chatter_answers_question_escalation_to_case_trigger</members>
<name>ApexTrigger</name>
</types>
<version>37.0</version>
</Package>
When I deployed my actual package, I marked these files as deleted thus making sure it does not interfere in my future code coverage.
Question
is the problem as that SObject is documented to be in V37.0. But if the trigger refers to any sobject or sobjectfield that was introduced in V37 and your prod org is still at v36, then this error could occur if your sandbox was at v37.