Layer error: reduce.median: Error in map(ID=null): Image.normalizedDifference: Expected exactly 2 band names

Question

I tried to create a land composite for mangroves in my study area. The code works fine for creating land composite map using Landsat 8, and when i modify the code for Landsat 7 images, i encounter this error.

Here is my code.

var L7 = ee.ImageCollection("LANDSAT/LE07/C02/T1_L2");
var addIndicesL7 = function (img) {
  var ndvi = img.normalizedDifference (['SR_B4, SR_B3']).rename ('NDVI');
  var ndmi = img.normalizedDifference (['SR_B7, SR_B2']).rename ('NDMI');
  var mndwi = img.normalizedDifference (['SR_B2, SR_B5']).rename ('MNDWI');
  var sr = img.select (['SR_B4']).divide(img.select(['SR_B3'])).rename ('SR');
  var ratio54 = img.select (['SR_B5']).divide(img.select(['SR_B4'])).rename ('R54');
  var ratio35 = img.select (['SR_B3']).divide(img.select(['SR_B5'])).rename ('R35');
  var gcvi = img.expression ('(NIR/GREEN)-1', {
     'NIR':img.select ('SR_B4'),
     'GREEN':img.select ('SR_B2')
   }).rename ('GCVI');
   return img
   .addBands (ndvi)
   .addBands (ndmi)
   .addBands (mndwi)
   .addBands (sr)
   .addBands (ratio54)
   .addBands (ratio35)
   .addBands (gcvi);
   };

 var year = 2021; 
 var startDate = (year-1)+'-01-01'; 
 var endDate = (year+1)+'-12-31'; 


var l7 = L7.filterDate(startDate,endDate)
     .map(maskClouds)
     .map(addIndicesL7);


 var L7composite = l7
               .median()
               .clip(studysite); 

Answer 1

This wouldn't work for L8 either. normalizedDifference() expects a list with two band names. You provided it with

['SR_B4, SR_B3']

This is a list with with a single string. You want

['SR_B4', 'SR_B3']