1. Attempting to update an array using dotted notation failed with a PathNotViable error (code 28) if the array is sufficiently large.

Attached is a jstest that creates an empty array, then attempts to insert 10 new elements into the array using dotted notation such as {$set: {"array.0.content": "x"}}: PathNotViable.js

 The test will fail if we attempt to insert 10 elements at once. It will succeed when we try to insert fewer than that, e.g. 9 elements.

The error message printed in the console is as follows:

Cannot create field 'content' in element {: null}
WriteResult({
  "nMatched": 0,
  "nUpserted": 0,
  "nModified": 0,
  "writeError": {
    "code": 28,
    "errmsg": "Cannot create field 'content' in element {: null}"
  }
})

 This also happens when inserting the same number of elements using Pymongo.