title: Client side GroupBy is not supported
body: <p>I have the following Entity Framework Core 3.0 query:</p>
  
  <pre><code>var units = await context.Units
    .SelectMany(y =&gt; y.UnitsI18N)
    .OrderBy(y =&gt; y.Name)
    .GroupBy(y =&gt; y.LanguageCode)
    .ToDictionaryAsync(y =&gt; y.Key, y =&gt; y.Select(z =&gt; z.Name));
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>Client side GroupBy is not supported.
  </code></pre>
  
  <p>To run the query on the client, or part of it, I would do the following:</p>
  
  <pre><code>var units = context.Units
    .SelectMany(y =&gt; y.UnitsI18N)
    .OrderBy(y =&gt; y.Name)
    .AsEnumerable()
    .GroupBy(y =&gt; y.LanguageCode)
    .ToDictionary(y =&gt; y.Key, y =&gt; y.Select(z =&gt; z.Name));
  </code></pre>
  
  <p>Now it works.</p>
  
  <p>Why am I getting this error if I am not running the query on the client?</p>