Just a reminder that in Windows x64 Architectures, the machine.config file is located at c:\WINDOWS\Microsoft.NET\Framework64\v2.0.50727\config\machine.config.
Miguel Simões João
If you have larger solution packs, you must increase the maxRequestLength setting in the machine.config, under the httpRuntime element.
Typically, the recommended values are:
This setting also impacts the upload of files to your applciations, like excel files, or documents, so you should adjust it accordingly.
From my experience, you should avoid uploading solution packs larger than 80 MB, specially if uploading onto heavly loaded environments.