Strange issue with deserialising streamed content of length exactly equal to a power of 2

[andrew-tevent]

I've got this strange issue when deserialising a fairly large (32768 bytes = 2^15) amount of JSON.

The issue I have is that the deserialisation fails when the content is exactly this size. The same if I have exactly 65536. Just one byte more or less and it is fine.

If I set the JsonSerializerOptions.DefaultBufferSize to something bigger than the content then it all works fine.

So the issue seems to be due to partial JSON.

I don't have the full stack trace, but this is the Exception message:

'Cannot skip tokens on partial JSON. Either get the whole payload and create a Utf8JsonReader instance where isFinalBlock is true or call TrySkip.'

I'm sorry, I don't have full example or details at the moment. The content being deserialised is fairly complex, and has a list of polymorphic types using the Discriminator. I've tried to create a basic example without polymorphism, but it doesn't have this same issue.