CosmosDB Invalid BSON With Update using $ [duplicate] - mongodb

Question

Embedded Update query works fine in mlab and atlas but not working in Cosmos DB:
My Collection structure:
{
"_id" : ObjectId("5982f3f97729be2cce108785"),
"password" : "$2y$10$F2P9ITmyKNebpoDaQ1ed4OxxMZSKmKFD9ipiU1klqio239c/nJcme",
"nin" : "123",
"login_status" : 1,
"updated_at" : ISODate("2017-05-16T09:09:03.000Z"),
"created_at" : ISODate("2017-05-16T06:08:47.000Z"),
"files" : [
{
"name" : "abc",
"updated_at" : ISODate("2017-05-16T06:08:48.000Z"),
"created_at" : ISODate("2017-05-16T06:08:48.000Z"),
"_id" : ObjectId("5982f3f97729be2cce108784")
}
],
"name" : "demo",
"email" : "email#gmail.com",
"phone" : "1231234",
}
My query is:
db.rail_zones.update(
{'_id': ObjectId("5982f3f97729be2cce108785"),
'files._id' : ObjectId("5982f3f97729be2cce108784")},
{ $set: {'files.$.name' : "Changed"}})
I get this response:
"acknowledged" : true,
"matchedCount" : 0.0,
"modifiedCount" : 0.0

Answer 1

According to your description, I tested this issue on my side and found the Array Update could not work as expected. I assumed that the Array Update feature has not been implemented in the MongoDB Compatibility layer of Azure CosmosDB. Moreover, I found a feedback Positional array update via '$' query support talking about the similar issue.