QuickBooks error 6123 arises at the time of upgrading the QuickBooks company files to the latest edition. If you are also going through the same issue and want some fix solution, we advise you to disable the antivirus program & security software. And then, try to attempt the following solutions. Causes behind QuickBooks Error 6123 Under-mentioned are some of the probable causes that are responsible for the occurrence of QuickBooks error code 6123 0. 1. You will be unable to communicate with the server due to the firewall security program. 2. Because of the damaged Windows OS version, you can get QuickBooks error 6123 0. 3. If you turn on hosting on your PC, QuickBooks error 6123 0 arises. Solutions to troubleshoot QuickBooks Error 6123 Firstly, we recommend you to detect the case in which you are getting QuickBooks error code 6123 0. After that, attempt the solutions accordingly to get rid of the same. Solution 1: Download the QuickBooks Tools Hub 1. Firstly, close the QuickBooks software and install the QuickBooks Tool hub. 2. After that, you need to launch the recently downloaded file named QuickBooksToolHub.exe. 3. Follow the instructions in order to accept the terms and conditions. 4. Finally, you need to click on the icon to open the tool hub. Solution 2: Try to run “Quick fix my Program” 1. First of all, click on Program Problems. 2. You are required to choose Quick Fix my Program. 3. You need to wait until the QuickBooks tool launches. In case, you have installed multiple versions of QuickBooks in your PC, then the tool can take more time to find the QB errors. 4. Finally, try to open the QuickBooks application. To sum up We hope that you have resolved QuickBooks Error 6123 after going through all the aforementioned solutions. Sometimes, users may find it difficult to deal with bugs or errors on their own. But, you don’t need to take stress at all. You just need to dial our toll-free QuickBooks Premier Support Phone Number(+1-888-660-0607)(Toll- Free).