You may run into this validation error when deploying changes to SearchSettings metadata type.

For example, on below screenshot we're seeing:
​"Entity is null or entity element's name is null"

This error indicates that SearchSettings metadata in its XML file refers to an object that either doesn't exist or is not accessible in the target org. Salesforce calls an object "an entity".
​

The SearchSettings metadata defines which objects are searchable and how they behave in search results.

Based on that understanding, it's possible that one or more objects listed in SearchSettings metadata aren't present in the target org to which you're deploying.

In below example, when we checked the comparison of the failing pull request in Gearset Pipelines, we learned that SearchSettings metadata (which is referred to as Settings) was referencing an object (ActiveScratchOrg) which was not present in the target org.

This can be easily confirmed by searching for the object name in the Search bar (top right corner), which would surface the same object as a new component in comparison results.

If you've come across this error during PR (pull request) validation in your Gearset Pipelines, consider below workarounds which should help you address the issue.

Similarly as on the above example (see screenshots), once you have identified the object(s) which are showing up as new in your source environment (e.g. on a feature branch > org comparison), consider the following steps:

​1) If you're working with Gearset Pipelines, deploy the missing object(s) to the target org as part of a "New feature" (PR).

2) Consider deploying each object individually by committing every object to a brand new feature branch, and then in your Gearset Pipeline open a new PR against the environment that represents your target org (e.g. INT/UAT/QA etc).

3) Once all missing objects are successfully deployed to the target org, try to re-validate the original PR that failed the validation for SearchSettings. The expectation here is that the validation succeeds this time.

Once you've confirmed which object(s) the SearchSettings metadata is referencing, and verified which of these objects are not present in the target org, consider the following steps:

1) In the XML file find <searchSettingsByObject> block where the <name> tag references the object(s) that are not present in the target org.

2) Then remove these lines of code from your feature branch. You're looking at removing an entire reference to the object which should look like this:

​<?xml version="1.0" encoding="UTF-8"?>
​<SearchSettings xmlns="http://soap.sforce.com/2006/04/metadata">
​ <searchSettingsByObject>
​ <searchSettingsByObject>
​ <enhancedLookupEnabled>true</enhancedLookupEnabled>
​ <lookupAutoCompleteEnabled>true</lookupAutoCompleteEnabled>
​ <name>ActivateScratchOrg</name>
​ <resultsPerPageCount>25</resultsPerPageCount>
​ </searchSettingsByObject>
​...
</SearchSettings>

​3) Once the feature branch is updated, try to re-validate your original PR in the Pipeline.

Tip: If you're not sure which object is causing the error, you can use a process of elimination. Remove half of the <searchSettingsByObject> entries (or only one entry with a specific object), and try to re-validate the PR.
​
If PR validation succeeds, that means the bad entry was in the half you removed. If it fails, then bad entry is present in the half of code you kept. Repeat this process until you isolate the single problematic entry (object).

If you're using our Compare and deploy tool to push the SearchSetting and have run into this error, you can still apply both of the above workarounds - except that you wouldn't be making deployments in the Pipeline, but instead:

The root cause of this error is usually a mismatch in object availability between the source and target orgs. This includes:

More information on this error can be found on Salesforce StackExchange forum.