Written ByDavid HernandezSenior Technical Writer

Reviewed ByPatricia WalshFormer Intuit Technical Support Lead

QuickBooks Error 6123, 0: "Connection to the Company File Has Been Lost"

Six Proven Fixes, Simplest First

You click to open your company file, or you're halfway through restoring a backup, and QuickBooks stops with Error 6123, 0. The message says the connection to the company file has been lost, and nothing you click seems to bring it back.

It's frustrating, especially when you've got invoices to send or payroll to run. The good news is that this error almost never means your data is gone. It means QuickBooks lost its grip on the file for a moment, and something is stopping it from getting that grip back. Once you clear that obstacle, the file usually opens normally.

"We're sorry, but QuickBooks can't open your company file. Error -6123, 0. Connection to the QuickBooks company file has been lost."

What's in This Guide:

▶ What Is QuickBooks Error 6123, 0?

▶ Why Does Error 6123 Happen?

▶ Quick Reference: Which Fix Should You Try?

▶ How to Stop Error 6123 From Coming Back

▶ FAQs

Business owner troubleshooting a lost connection to a QuickBooks company file

What Is QuickBooks Error 6123, 0?

Error 6123 is QuickBooks telling you it started talking to your company file (the .QBW file) and the conversation got cut off. It belongs to the -6000 family of errors, which are all about QuickBooks having trouble opening or reading the company file.

You'll usually run into it in one of these situations:

Opening a company file that lives on a server or another computer on your network
Restoring a backup (.QBB) or a portable company file (.QBM)
Upgrading a company file to a newer version of QuickBooks Desktop
Opening a file right after Windows installed updates
Opening a file that was copied from a USB drive or cloud folder

Your data is probably safe. Error 6123 is a connection problem, not a sign that your books are wiped out. Don't start re-entering transactions or deleting files. Work through the fixes below in order first.

Why Does Error 6123 Happen?

In our experience, almost every case of Error 6123 comes down to one of these causes. Knowing which one fits your situation can save you a lot of time.

Your antivirus or firewall is cutting the connection

Security software watches every file that gets opened. When QuickBooks opens a large company file, especially over a network, antivirus programs like McAfee, Norton, Bitdefender and Avast sometimes step in and block part of the connection. QuickBooks sees the file disappear mid-conversation and throws Error 6123.

The company file name is too long or has special characters

QuickBooks is fussy about file names. If your file is called something like "Smith & Sons Plumbing, LLC (2019-2024) FINAL copy.qbw", the ampersand, comma and parentheses can trip it up. Very long file paths cause the same trouble.

The file is stored somewhere QuickBooks doesn't like

Company files kept in OneDrive, Dropbox or Google Drive folders, on USB drives, or on network-attached storage that isn't set up for QuickBooks are a common source of this error. Sync tools lock and copy the file while QuickBooks is trying to use it.

Multi-user hosting is set up wrong

If more than one computer thinks it's the host, or the server isn't running QuickBooks Database Server Manager, the workstations lose their connection to the file. This is the number one cause in offices with two or more QuickBooks users.

The company file or QuickBooks installation is damaged

A power cut, a crash during a backup, or an update that didn't finish properly can leave the file or the program itself in a bad state. This is less common than the causes above, but it does happen.

How to Fix QuickBooks Error 6123, 0, Step by Step

Start with Fix #1 and work down. Most people are back in their books by Fix #3. Before you start, make sure QuickBooks is closed on every computer in the office.

FIX #1

Run Quick Fix My File and File Doctor from the QuickBooks Tool Hub

The QuickBooks Tool Hub is Intuit's free repair kit, and it fixes a big share of -6000 series errors on its own. If you don't have it yet, it takes about two minutes to install.

Step 1 Download the latest QuickBooks Tool Hub from Intuit's website and save it somewhere easy to find, like your Downloads folder.

Step 2 Open the downloaded file (QuickBooksToolHub.exe), accept the license agreement and follow the prompts to install it.

Step 3 Open the Tool Hub from the icon on your Windows desktop and click Company File Issues.

Step 4 Click Quick Fix my File and wait for it to finish. When it says it's done, try opening your company file. If the error is still there, go back to the Tool Hub.

Step 5 Click Run QuickBooks File Doctor. Choose your company file from the list (or browse to it), select Check your file and network, and click Continue.

Step 6 Enter your QuickBooks admin password when asked, then click Next. Large files can take 10 to 20 minutes, so let it run. When it finishes, open QuickBooks and try your file again.

Tool Hub updates regularly. If you installed it a while ago, uninstall it and download a fresh copy so you're using the newest repair tools.

FIX #2

Rename the Company File and Move It to Your C: Drive

This fix clears up file name problems and storage location problems in one go. It takes about five minutes.

Step 1 Open the folder where your company file lives. If you're not sure where it is, open QuickBooks, press F2 on the No Company Open screen, and look at the File Information line for the full path.

Step 2 Find your company file. It ends in .QBW. You may also see a matching .QBW.TLG file and a .ND file with the same name.

Step 3 Right-click the .QBW file and choose Rename. Give it a short, simple name with only letters and numbers, like SmithPlumbing.qbw. Rename the .TLG file the same way, keeping its extension.

Step 4 Create a new folder directly on your C: drive, for example C:\QBData, and copy the renamed file into it.

Step 5 Open QuickBooks, choose Open or restore an existing company, browse to the new folder and open the file.

Before:  C:\Users\Sam\OneDrive\Books\Smith & Sons Plumbing (2019-2024) FINAL.qbw
After:   C:\QBData\SmithPlumbing.qbw

Important: Copy the file, don't move it, until you've confirmed it opens. That way the original stays untouched as a fallback.

FIX #3

Turn Off Your Antivirus for a Test, Then Add QuickBooks Exclusions

If the file opens fine with your antivirus switched off, you've found the culprit. The goal isn't to leave your computer unprotected. It's to tell your antivirus to leave QuickBooks alone.

Step 1 Right-click your antivirus icon near the clock in the bottom-right corner of the screen and choose the option to pause or disable protection for 15 minutes.

Step 2 Open QuickBooks and try the company file. If it opens, close QuickBooks and turn your antivirus back on straight away.

Step 3 Open your antivirus settings and find the exclusions (sometimes called exceptions or allowed apps) section.

Step 4 Add your QuickBooks program folder, usually C:\Program Files\Intuit\QuickBooks 20XX, and the folder that holds your company file.

Step 5 Also add these program files as allowed: QBW32.exe, QBDBMgrN.exe, QBCFMonitorService.exe and QBUpdate.exe. Save the settings and try your file again with protection turned on.

FIX #4

Open a Sample Company File to Narrow Down the Problem

This quick test tells you whether the trouble is with your company file or with QuickBooks itself. It doesn't change anything, so it's safe to try.

Step 1 Open QuickBooks so you're on the No Company Open screen. If QuickBooks opens your file automatically, hold the Ctrl key while it starts.

Step 2 Click Open a sample file and pick any sample company from the list.

Step 3 If the sample opens with no error, QuickBooks is working and the problem is with your company file or where it's stored. Go back to Fix #2, or restore a recent backup to your C: drive.

Step 4 If the sample company also shows an error, the QuickBooks installation is damaged. Skip ahead to Fix #6.

FIX #5

Check Your Multi-User Hosting Setup

If your company file lives on a server or a shared computer, a hosting mix-up is a likely cause. Only the computer that stores the file should host it.

Step 1 On every workstation (the computers that don't store the file), open QuickBooks, go to File > Utilities, and look at the hosting option. If it says Stop Hosting Multi-User Access, click it. Workstations should say Host Multi-User Access, which means they're not hosting.

Step 2 On the server (the computer that stores the file), open the Tool Hub, click Network Issues, then QuickBooks Database Server Manager.

Step 3 Click Browse and select the folder that holds your company file, then click Start Scan. This sets the folder permissions and makes sure the file can be shared.

Step 4 When the scan finishes, open QuickBooks on a workstation and try the file again.

If your office keeps having hosting problems, our guide to Error H202 walks through the full multi-user setup in more detail.

FIX #6

Repair or Clean Install QuickBooks Desktop

If the sample company file failed in Fix #4, the problem is QuickBooks itself. A repair keeps your settings; a clean install starts fresh. Your company file isn't touched either way, but make a backup first anyway.

Step 1 Have your license number and product number ready. You'll find them in your purchase email, or press F2 in QuickBooks to see them on the Product Information screen.

Step 2 Open the Windows Control Panel, go to Programs and Features, select QuickBooks and click Uninstall/Change. Choose Repair and follow the prompts.

Step 3 If the error comes back after a repair, uninstall QuickBooks completely from the same screen.

Step 4 Open the Tool Hub, go to Installation Issues, and run the Clean Install Tool. It renames the leftover QuickBooks folders so the new install starts clean.

Step 5 Reinstall QuickBooks from your download link and enter your license and product numbers. Our download and installation guides have the official installer links for every version.

Quick Reference: Which Fix Should You Try?

Your situation	Best fix to try first	How often it works
Error appears on every computer in the office	Fix #5: check multi-user hosting	Very often
File is in OneDrive, Dropbox or on a USB drive	Fix #2: rename and move to C: drive	Very often
Error started right after an antivirus update	Fix #3: antivirus exclusions	Often
Error appears when restoring a backup	Fix #2, then restore to a new folder	Often
Sample company file also fails	Fix #6: repair or clean install	Very often
You're not sure	Fix #1: Tool Hub and File Doctor	Often

How to Stop Error 6123 From Coming Back

Once you're back in, a few habits will keep this error away for good.

Keep company files out of sync folders. OneDrive, Dropbox and Google Drive are great for documents, but they fight with QuickBooks over the company file. Keep the live file on your C: drive or a proper server, and back it up to the cloud separately.
Use short, plain file names. Letters and numbers only. Save the full business name for inside QuickBooks.
Close QuickBooks at the end of the day. Overnight backups and Windows updates are much less likely to damage a file that isn't open.
Keep QuickBooks updated. Go to Help > Update QuickBooks Desktop once a month. Updates fix many of the bugs behind -6000 series errors.
Back up before every upgrade. Upgrading a company file to a newer version is one of the riskiest moments for this error. A fresh backup means you can always go back.

Frequently Asked Questions About Error 6123, 0

Will I lose my data if I get Error 6123?

Almost certainly not. Error 6123 is about QuickBooks losing its connection to the file, not about the data inside being erased. In the rare cases where the file is damaged, File Doctor can usually repair it, and you can always restore your most recent backup.

Why do I get Error 6123 only when restoring a backup?

Usually it's the location or the name. Restore the backup to a brand-new folder on your C: drive and give the restored file a short name with no special characters. If that still fails, the backup itself may be damaged, so try an older backup if you have one.

Does Error 6123 happen in QuickBooks Pro, Premier and Enterprise?

Yes. It can show up in every QuickBooks Desktop edition, from Pro to Enterprise, and in older and newer versions alike. The fixes on this page work for all of them.

I fixed it but it came back the next day. What's going on?

Something is undoing the fix overnight. The usual suspects are a sync tool moving the file again, an antivirus update that wiped your exclusions, or a second computer that's been set to host multi-user access. Check those three first.

My QuickBooks version is really old. Could that be the problem?

It can be. Older versions like QuickBooks 2018 and earlier no longer get updates from Intuit and can struggle on Windows 11. If you're on an unsupported version, upgrading may be the real fix. We have one-time purchase QuickBooks Desktop licenses with no subscription.

If you've worked through everything above and the error won't go away, don't keep fighting it alone. Give us a call or send an email. We see QuickBooks Desktop errors like this every day and we're happy to point you in the right direction.

Still Stuck on Error 6123? Talk to Us.

We're real people who know QuickBooks inside and out.

Phone: (870) 232-6314

Email: info@accountingscart.com

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