Graph API To Update User Photo Throws error

Using Graph API, I am updating user photo in Delve. It is working fine for some times .

But randomly it get failed for same photo and give status as Faulted.

It is giving error like below:

Message: The maximum request length supported is 4MB.

What size limitation do we have to upload the photo?

Is there any alternative for the same?

Any pointers would be appreciated.