This error is generally caused when the eFileCabinet Client does not update correctly.  

To fix this error:
1. Close the eFileCabinet client.  
     For Windows 7 or newer go to C:\ProgramData\eFileCabinet\5 and rename the client_settings.edb file. 

    For Windows XP go to C:\Documents and Settings\All Users\Application Data\eFileCabinet\5 and rename the client_settings.edb file.  
2. Re-open the eFileCabinet client and log in again.  
3. You will be prompted to update the client.  

After the update, the issue should be resolved.  Please contact support if this does not resolve the issue.

Note:  ProgramData and Application Data are hidden folders by default.  To un-hide the folder go to Control Panel>Folder Options>View tab.  Check the option next to "Show hidden files, folders, and drives" or "Hidden items" in Windows 10.