First, let's tackle the immediate error you're facing: the "Script function not found" message when clicking your custom menu. This is a straightforward fix related to how you're registering the menu item.

The Main Issue #

When using addItem to create a menu entry, the second parameter needs to be a string matching your function's exact name—not the function reference itself. In your original code, you passed mergeDuplicates directly instead of wrapping it in quotes as a string.

Corrected onOpen Function #

function onOpen() {
  var ui = SpreadsheetApp.getUi();
  var menu = ui.createMenu('Custom Menu');
  // Pass the function name as a quoted string here
  menu.addItem('Merge Duplicates', 'mergeDuplicates')
      .addToUi();
}

Bonus Fix: Duplicate Notes Not Combining #

Once you fix the menu error, you'll notice your script still doesn't merge notes correctly. That's because concat() returns a new string but doesn't update the value stored in your notesByName object. You need to assign the concatenated result back to the object key. I also added a separator (comma + space) to make combined notes more readable:

Updated mergeDuplicates Function #

function mergeDuplicates() {
  var target = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = target.getSheetByName("Test");
  var lastRow = sheet.getLastRow();
  var dataRange = sheet.getRange(2, 1, lastRow - 1, 2);
  var data = dataRange.getValues();
  var notesByName = {};

  for (var i = 0; i < data.length; i++) {
    var row = data[i];
    var curName = row[0];
    var curNote = row[1];

    // Skip rows with empty names
    if (!curName.trim()) {
      continue;
    }

    // Initialize note for first occurrence of the name
    if (!notesByName[curName]) {
      notesByName[curName] = String(curNote);
    } 
    // Append note for duplicate names (with a separator)
    else {
      notesByName[curName] = notesByName[curName].concat(', ', curNote);
    }
  }

  // Format data for output
  var outputData = Object.keys(notesByName).map(function(name){
    return [name, notesByName[name]];
  });

  // Clear old data and write merged results
  dataRange.clearContent();
  var newDataRange = sheet.getRange(2, 1, outputData.length, 2);
  newDataRange.setValues(outputData);
}

How to Apply the Fixes #

1. Replace your existing functions with the updated versions above.
2. Save your script, then refresh your Google Sheet.
3. The "Custom Menu" will now appear, and clicking "Merge Duplicates" will run the function without errors—correctly combining notes for duplicate names.

内容的提问来源于stack exchange，提问作者IWI