title: how to resolve Power BI error - the key didn't match any rows in the table
body: <p>I am trying to load (combine) multiple Excel files into Power BI (October 2019 version).  Every file has only 1 sheet.  Each sheet has 1 range, and each range has the same schema across all files.  (The sheet names are different, though.)  A sample sheet name is '200704'.</p>
  
  <p>Here are my steps:</p>
  
  <ol>
  <li>Get Data \ Folder \ Connect </li>
  <li>specify the Folder path</li>
  <li>Combine &amp; Load</li>
  <li>select one of the files as my sample file; click on the file name as
  my Parameter1; click OK</li>
  </ol>
  
  <p>After I click OK, the cursor spins for a bit, and then it stops.  Nothing happens.  So, I go to Edit Queries \ Edit Queries.  There is a warning symbol on my data query that reads:</p>
  
  <blockquote>
    <p>An error occurred in the 'Transform File' query.  Expression.Error:
    The key didn't match any rows in the table. </p>
    
    <p>Details: Key = Item=200704 Kind=Sheet Table=[Table]</p>
  </blockquote>
  
  <p><strong>How do I resolve this error?</strong></p>
  
  <p>If it helps, Power BI generate 5 queries for me, and the structure is:</p>
  
  <ul>
  <li>Transform File from data [2]</li>
  <li>Helper Queries [3]</li>
  <li>Parameter1 (Sample File)</li>
  <li>Sample File</li>
  <li>Transform File</li>
  <li>Transform Sample File</li>
  <li>Other Queries [1]</li>
  <li>data</li>
  </ul>
  
  <p>Interestingly, if it helps to diagnose the issue, if I set sample file = First file or if I set sample file to my first file manually, the following error is thrown in the dialog, but it doesn't show what query is in error when I try to view / edit the query.</p>
  
  <blockquote>
    <p>Failed to save modifications to the server.  Error returned: 'OLE DB or ODBC error: [Expression.Error] The key didn't match any rows in the table..'.</p>
  </blockquote>
  
  <p>And, to be sure, when I attempt to load this file (or any file in the folder, for that matter) individually (via Excel connection), it loads successfully.  So, something must be wrong with the M code in my Folder connection.</p>