Cannot upload a file larger than 7 MB over TLS 1.0 to a server that is running IIS

Symptoms

On a computer that is running Windows Vista, Windows 7, or Windows Server 2008 R2, you may be unable to upload a file larger than 7 megabytes (MB) over Transport Layer Security (TLS) 1.0 to a server that is running Internet Information Services (IIS). The issue occurs with non-Microsoft clients only. A network trace between the client and server shows that the IIS TCP window size drops to 0 (zero), and the server cannot recover.

Cause

The issue occurs because the HTTP module does not account for the unnecessary 0 bytes buffer. This creates a condition in which HTTP can no longer accept data from the TCP layer. Therefore, the TCP window size drops continuously and does not recover.

Resolution

To resolve this issue, switch to a later version of TLS.
Properties

Article ID: 3056424 - Last Review: Jun 22, 2015 - Revision: 1

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