A few days ago we’ve got a strange “413” error while we’re testing our provider hosted application on our SP 2013 development environment. The description of the error is “Request Entity too large” which doesn’t make sense because as the description implies we know that this error can occur while a really large request is sent to the server like uploading a file. In our case we’re just sending an ASP.NET page to the server.
After some googling we’ve found that this error can be caused by SSL which is used in provider hosted apps. So after we’ve added the followinf lines just before the tag in web.config, the error was gone.
<location path="THENAMEOFTHESITEYOUHAVE" overrideMode="Allow">
<serverRuntime uploadReadAheadSize="2147483647" />