DFS 9.0.0 - RTE, The command dfsexplorerMedia is not implemented yet

If you experiences this error in rich text editor (RTE) when inserting an asset, then is is most likely because a specific JavaScript file has not been loaded (DFS.RTE.min.js).

DAM for Sitecore (DFS) requires this file. The reason why is has not been loaded is because of a patch merge conflict in the configuration files. Take a look at this configuration files \App_Config\Include\damforsitecore\DFS.Client.config and search for clientscripts. It should look like this.

<clientscripts>
   <htmleditor>
      <script src="/Shell/Controls/RichTextEditor/DFS.RTE.min.js" language="javascript" key="customJs" />
   </htmleditor>
</clientscripts>

Now go to you Sitecore instance an run /sitecore/admin/showconfig.aspx. Search for <clientscripts>. In the below example you can see that DFS.RTE.min.js is missing. In this case the patch file Sitecore.XA.Feature.ContentTokens.config overwrites the DFS configuration. Because is is loaded after DFS config.

<clientscripts>
	<everypage/>
	<htmleditor>
		<script key="customJs" src="/sitecore/shell/Controls/Rich Text Editor/Insert Content Token Commands.js" language="JavaScript" patch:source="Sitecore.XA.Feature.ContentTokens.config"/>
	</htmleditor>
</clientscripts>

Solution

Locate the config file that contains the <clientscripts> tag and insert the <script src="/Shell/Controls/RichTextEditor/DFS.RTE.min.js" language="javascript" key="customJs" />, save the file. Now load showconfig.aspx again and verify that that both scripts are added to <clientscripts>. If that is the case, you should be able to insert assets again to RTE.