Not only QB Error code 2003 but also 5502 & 5503 are the errors categorized under when the QB data has been uploaded, but failed to connect with the server. Get the full details of QuickBooks Error code for more specification.
Error Message
For smooth fixation of the QuickBooks Error 2003 please follow the following solution.
Firstly you need to double-click on the desktop QuickBooks File Doctor Icon.
If you have problems opening your file over a network or multi-user problems, edit the Advanced Settings to run the Network Diagnosis only
Click browse, navigate to your company file and click open
Click the Diagnose file button.
System Requirements:
QBFD Tool supports: Win 8, Win 7, Win Vista, Win XP SP3, WinXP SP2
.NET frame work 2.0 (if is not installed on your system, it will be installed along with the diagnostic tool).
• User Account Control settings (UAC) – The network diagnosis only occurs if UAC is turned off. You should return UAC to its original settings when the tool is finished.
File Repair: QuickBooks does not need to be installed on your computer.
Network diagnosis and repair: You must be logged into Windows as Administrator.
Multi-user diagnosis and repair: QuickBooks Hosting must be turned on (only on the computer hosting the company files).
If this solution does not resolve the issue or answer your question, you can read discussions and post messages and questions relating to your issue on the Intuit QuickBooks Community site introduced by Intuit or you can connect with the QuickBooks support for guidance and error fixation.