How to Fix QuickBooks Multi-User Mode Not Working Issue?
QuickBooks Multi User Mode
QuickBooks multi user mode is an inbuilt feature in QuickBooks that permits multiple users to work on the same company file at the same time. This feature helps in increasing collaboration and enhances productivity.

Each user must have the QuickBooks license to use the multi-user mode in QuickBooks. The issue with QuickBooks desktop multiple users mode arises when the user is trying to launch the company file which has been located on another PC. In this case, you may not receive any error but it will automatically display on another computer.

What causes QuickBooks multi-user mode not working problem?
There can be a number of reasons that can cause the appearance of multi-user mode QuickBooks –

QuickBooks is not installed on the server.
The hosting settings are not properly configured.
Firewall or antivirus software is not allowing communication between user computers.
The database server is unable to open the QuickBooks company file.
Windows file permissions are not properly set.
Solutions to Fix QuickBooks multi-user mode not working issue
You may face QuickBooks multi-user mode not working problem after you have completed QuickBooks multi-user setup for using QuickBooks in multi-user mode. This problem is associated with errors such as H101, H202, H303, and H505. Following solutions can help you in fixing this issue:

Use QuickBooks File Doctor
Download the QuickBooks File Doctor tool from the Intuit website and run it. This tool analyzes whether your computer is properly set up for using multi-user mode or not. After running the tool, check whether you are facing QuickBooks multi-user mode not working problem.

Use QuickBooks Database Server Manager
Open QB Database Server Manager in your server computer by typing database in the Start menu.
If you find no folder locations, use Browse to go to the folder storing company file/files.
Hit the OK button and then click the Scan button.
By following the above steps, firewall permissions will get repaired. Now, check whether QuickBooks multi-user mode not working problem has resolved.

Check to host mode on each of the user computers
On a user computer, open QuickBooks File menu and then Utilities. If Host Multi-User Access appears on the list, move to the next computer as this means this computer is not hosting company file. If in case, Stop Hosting Multi-User Access appears on the list, select it to disable hosting and enable QuickBooks single user mode.

After you have ensured that hosting mode is off on all user computers, check for the QuickBooks multi-user mode not working error.

Check whether QuickBooks services are running
To use QuickBooks in multi-user mode, QuickBooks services–QuickbooksDBXX (XX represents the year of QuickBooks) and QBCFMonitorService- should be in running state on the server computer.

On the Windows search bar, type services.msc and hit Enter.
See if QuickBooksDBXX service appears in the Services window. If it is not appearing, follow these steps –
If you only make use of Database Server Manager, then ensure that it is installed on the server. For each year of QuickBooks Desktop installed on the workstation, there should be installed the corresponding Database Server Manager.
If in case, the entire program is run on the computer, ensure hosting is enabled on the server.
Double-click QuickBooksDBXX service. Under Startup type on the screen, the value should be Automatic. Service started should show Running or Start.
Under the Recovery tab, you have to choose to restart the QuickBooksDBXX service for the first, second and subsequent failures.
Repeat the above-mentioned steps 1 to 4 for the QBCFMonitorService.
Now, open QuickBooks in multi-user mode on each of the user computers to see if QuickBooks multi-user mode not working issue is solved or not. If the problem is still occurring, check membership of QuickBooksDBXX service. It should be a part of the administrator group. Also, it should have all the necessary permissions.

Make sure QuickBooks can send data
This solution has two steps –

Change settings of firewall or antivirus software
If the firewall is the cause of QB multi-user mode not working issue, you have to manually set up exceptions in the firewall for ports that QuickBooks software uses for transmitting data. If antivirus software is leading to the error, configure it to resolve the issue.

Perform file path testing to check if QuickBooks can communicate with the server
For this, Network Discovery should be turned on and the name of the server should be known. Follow these steps –

Enter ping [servername] in the Run command and hit the Enter button.
Use the Universal Naming Convention (UNC) path from the user computer to go to the shared folder in server.
To go to the QuickBooks company file, make use of the UNC path.
Create a new company file folder
This solution requires the creation of a new folder for the company file on the hosting computer. Set up folder and Windows access permissions for the new folder so that company files can be shared. Copy the .qbw file to the new folder and check whether you are able to open the company file in multi-user mode.QuickBooks Multi User Mode Not Working problem may have been resolved.