You may recieve the error during the deployment of a Reporting Services model:
There was an exception running the extensions specified in the config file.Maximum request length exceeded.
To correct, you need to increase the file size limit currently in place in the web.config on the RS Server. Find the web.config file located in the directory:
[SQL Server Directory]/[MSSQL RS Instance]/Reporting Services/ReportServer
Locate the node <httpRuntime> and add the attribute maxRequestLength and a number, or simply modify the value until you increase the limit such that you can deploy.
Mine looked like this when I was done:<httpRuntime executionTimeout = "9000" maxRequestLength = "102400" />
Save the file and redeploy. You can switch it back if you like when you are done deploying.
Full attribute listing for httpRuntime here:http://msdn.microsoft.com/en-us/library/e1f13641(VS.80).aspx