I was asked today to add a file to a page. The file itself was only 6Mb, and MCMS was having none of it. Digging around, I found the problem wasn’t actually MCMS itself, but the underlying ASP.

It turns out you need to add the following to your web.config file, to change the maximum file size that ASP accepts:
<httpRuntime
executionTimeout="3600"
maxRequestLength="10240"
useFullyQualifiedRedirectUrl="false"
minFreeThreads="8"
minLocalRequestFreeThreads="4"
appRequestQueueLimit="100">
</httpRuntime>
I’m not sure what all the settings do – but the executionTimeout is in seconds, and the maxRequestLength is in Kb.