I posted this in the developers forum as it sounds to me like an internal error rather than an error in the code but I've not received a response so I'm trying my luck here.
I'm trying to create a DOY band on an image collection. I found a similar question on stackexchange which includes a function for doing this (Add a date (day of year) band to each image in a collection using Google Earth Engine). This code works fine.
When I try to run the function on my ImageCollection I get an error message:
ImageCollection (Error) Error in map(ID=20170601T102019_20170601T102022_T33UUU): Image.date: Image does not have a valid system:time_start property!
This sounds to me like there is an error in the metadata in one of the images in my collection. Can anyone help solve this?
NB. 'aoi' is a multipolygon shapefile.
Here is a link to my code in gee: