Came across an interesting issue this week.  A customer encountered an unexpected error with the QuickBooks Web Connector after functioning just fine for months.  Based on the Log files, the system was throwing an exception when it tried to read the customers from QuickBooks and transfer the list to the AC7 web service.

After some really deep digging, the exception message was noted and revealed a curious limitation.  By default, SOAP commands/responses are limited to 4Mb in size.  Anything larger will throw an exception on the site.   This could easily happen on larger QB company files with a big customer or product list.

The solution is pretty simple: 

  1. MAKE A BACKUP OF YOUR WEB.CONFIG FILE FIRST! 
  2. Modify the Web.config file in the root of the site
  3. Find the <system.web> section and add a new line below it.
  4. Insert the command <httpRuntime maxRequestLength="8192" />
  5. Save the web.config file

The 8192 value represents an 8Mb limitation.  If this isn't enough, simply make it large enough to handle your particular needs.