Once done, you'll have to verify if the file you opened is correct. Make sure to open a company file with a .qbw extension at the end of the filename.
If the file is correct, let's turn off hosting on your workstations. If your file isn't hosted on a network, you can skip this step.
Open QuickBooks on one of your workstations.
Don't open your company file. Instead, select the File menu and hover over Utilities.
If you see the "Host Multi-User Access" option, don’t select it. Move on to the next workstation. This one isn’t causing the problem.
If Stop Hosting Multi-User Access is an option, select it.
Repeat these steps on all of your workstations.
After you check your workstations, move on to your server computer. This is the computer that normally hosts your company files.
Open QuickBooks on your server computer.
Open the File menu and hover over Utilities.
If Host Multi-User Access is an option, select it.
Toggle the setting. Repeat the process and select Stop Hosting Multi-User Access. This resets Multi-user Mode.
If the error persists, your company file’s location may be causing the issue. I suggest moving it to your Windows desktop and open it from there. For more details, see this article's Step 5: Move your company file section: Company File Won't Open.
Additionally, I've included an article that will help locate your company file if you're unable to locate it: Company File is Missing.
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