How Can I use QODBC with two different versions of QuickBooks installed?

Problem Description:

I have two different versions of QuickBooks (i.e., QuickBooks Enterprise 2012 & QuickBooks Enterprise 2014) installed on my machine.

I want to access both versions of QuickBooks using QODBC Auto Login.

I have configured QODBC Auto Login for both QuickBooks company files by creating two DSN & provide a company file path to both DSN. But I can access only QuickBooks 2014 company files using QODBC. I am unable to access QuickBooks 2012 company file using the QODBC auto-login. I am getting the below error when I try to connect QuickBooks 2012 company file using the QODBC auto login DSN, which I created earlier.

Solutions:

QODBC uses QuickBooks SDK to communicate with QuickBooks Company files. QuickBooks SDK requires QuickBooks UI to extract data from the Company file. Thus, when you have configured QODBC to run/use Auto Login to QuickBooks, QuickBooks UI will be loaded in the background, and the company file will be loaded on it (by QuickBooks SDK).

When there are multiple QuickBooks versions, QuickBooks SDK will start any of the QuickBooks versions. This is because the QuickBooks SDK does not know which Company file is associated with which QuickBooks (until the company file is opened).

For Example, You have installed QuickBooks 2012 & 2014 on a single Box.
Configured QODBC Auto Login for QuickBooks File for 2012 ( QODBC A).
Configured QODBC Auto Login for QuickBooks File for 2014 ( QODBC B ).

When QuickBooks is not running in the background.
Connecting to QODBC A - SDK can QuickBooks 2012 and click.
Connecting to QODBC B - SDK can QuickBooks 2014 and able to connect.

When QuickBooks 2012 is running in the background (QBW32 gets started on windows start - it's configurable in QuickBooks ).
Connecting to QODBC A - SDK can QuickBooks 2012 and able to connect.
Connecting to QODBC B - SDK can QuickBooks 2014 and NOT connect - as the company file is a new version.

When QuickBooks 2014 is running in the background (QBW32 gets started on windows start - it's configurable in QuickBooks ).
Connecting to QODBC A - SDK can QuickBooks 2012 and NOT connect - as the company file is a new version.
Connecting to QODBC B - SDK can QuickBooks 2014 and able to connect.

You are getting errors when you are trying to connect an older version of the company file. Because there is already QuickBooks exe for the 2014 version(QBW32.EXE) is already running in the background.

You can check it via the task manager.

So the solution is to remove QuickBooks from the auto start on windows start.
So if QBW32.exe (2012) is running, a connection cannot be made via QODBC DNS for the company file of 2014 ( QODBC B ).
So if QBW32.exe (2014) is running, a connection cannot be made via QODBC DNS for company file of 2012 ( QODBC A ).

QuickBooks is running in the background due to the option of "Keep QuickBooks running for quick start-up" under QuickBooks -- Edit Preferences -- General is enabled.

Please ensure you un-select the "Keep QuickBooks running for quick start-up" option under QuickBooks -- Edit Preferences -- General.

Please close all other QuickBooks instances of all other users and then try. (Please verify no instances are running of QBW32 under task manager --processes -- view all user processes)