You may receive the following error in Business Portal if you are on .Net version 4.0 in varying places if you have met maximum limits.

Server Error in '/' Application
Operation is not valid due to the current state of the object
Stack Trace:
System.web.httpvalueCollection.throwifMaxHttpCollectionKeysExceeded

In December 2011, Microsoft released a security update for ASP.NET.  In the update, Microsoft introduced a limit to the number of data elements on an ASP.NET form.  The default limit is 1000 data elements.  Exceeding the limit will cause a throwifMaxHttpCollectionKeysExceeded type error message.

After applying the patch, forms that exceed the limit will generate an error similar to what I have above.

To fix the issue in Business Portal, we need to make a change to the web.config file in the appSettings section.
Here are the steps:
1. Go to your web.config file on the Business Portal server.
Example location of mine
C:\inetpub\wwwroot\wss\VirtualDirectories\81
Make a copy of the file prior to editing.

2. Open the file in in notepad
Go to the bottom where you find this
<appSettings>

Add this below line in the web.config like I did to mine….I used 2000, use what you want so you will not exceed the limit in your environment.
<add key="aspnet:MaxHttpCollectionKeys" value="2000" />
Save and close the web.config file.

3. Click Start | Run type iisreset

Log back into Business Portal and you should not see the error message.

Example of mine:

Thanks!
Terry Heley