User gets an error message 'Operation is not valid due to the current state of the object' while using EngineerOffice/ArchiOffice 20xx, especially when the user is trying to save a change in the Preferences screen.
This error can be fixed in two ways depending upon its cause:
1. If this is a general communications error, it can be easily fixed on the server by going to the command prompt and doing an IISReset.
2. Go to the SQL Server Management Studio (SSMS) and Restart the server.
If you perform the above steps and the problem still persists, the cause maybe a problem with the settings in the web.config file. In that case:
1. Find the EngineerOffice web.config file at C:\Program Files (x86)\EngineerOffice 20xx\public
2. Open this file in Notepad. You should find an appSettings area in the web.config file with keys similar to those seen below, except that the value should be different.
3. Simply increase the value by 1000 for both entries and save your changes.
4. Now repeat the IISReset and SQL Server Restart outlined above in the first option.