Fix: File sharing lock count exceeded error

In Windows, there is certain limit for sharing files concurrently. If this threshold limit is exceeded, the fail sharing operation cannot be performed and you’ve have to give another try. There is a registry element which monitors and takes care of maximum file sharing limit and its called¬†MaxLocksPerFile entry. So when the file sharing limit is reached, you will receive following error:

File sharing lock count exceeded, Increase MaxLocksPerFile registry entry


We got this error while sharing business files via Microsoft Access. There is a big possibility that you came around this issue with Access specifically because chances of exceeding file sharing capability remains with this application. Sometimes a reboot of the system may help you to overcome this issue while in some cases you need to follow the mandatory steps to increase MaxLocksPerFile registry value as per the suggestion of error message.

Here is how to increase MaxLocksPerFile registry value:

These steps will involve registry manipulation. Making mistakes while manipulating the registry could affect your system adversely. So be careful while editing registry entries and create a System Restore point first.

1. Press Windows Key + R combination, type put regedit in the Run dialog box and hit Enter to open the Registry Editor.


2. Navigate here:

If you’re 32-bit Windows edition:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\x.0\Access Connectivity Engine\Engines\ACE 

If you’re 64-bit Windows edition:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Office\x.0\Access Connectivity Engine\Engines\ACE

Substitute the placeholder x.0 with 15.0 for Outlook 2013, 14.0 for Outlook 2010, 12.0 for Outlook 2007, and 11.0 for Outlook 2003.


3. In the right pane of this registry location, look for the MaxLocksPerFile named registry DWORD (REG_DWORD) whose default value is the root cause of this problem. The default value is 9500 in decimal base, so double click on the same DWORD to get this:


4. In the Edit DWORD Value box shown above, increase the Value data from default value as per your need, for example, set it to 15000. Make sure that the selected base is Decimal. Click OK. Close Registry Editor and restart Windows/File Explorer to make changes effective. Now try sharing files concurrently, and you won’t have any issues.

Let us know if this helps you!

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Posted by on , in Category Office with Tags
An Electrical Engineer by profession, Kapil is a Microsoft MVP and a Microsoft Content Creator. Please read the entire post & the comments first & create a system restore point before making any changes to your system.


  1. Mike F.

    I ran into this error while trying to learn access to manipulate a database of voter records. The size is 45,000 voters with 75 fields and each record is about 600 bytes. All I was trying to do was create a new field and copy another field into it. But I got the error message: “File sharing lock count exceeded. Increase MaxLocksPerFile registry entry.”
    The version of Access I am using is the latest and greatest (well maybe not greatest. I did not specify to the computer store which rebuilt my computer and I believe he sold me 32 bit Access) Windows 10 with Access 2016. The location of “MaxLocksPerFile appears to have been moved.
    From an ArcGIS help web site ( apparently ArcGIS makes it easy to change the setting with a built in menu unlike MSAccess) I located the Windows 10 Access 2016 location for MaxLocksPerFile:


    I changed the size from the default from 9,500 to 100,000 (some website said the max was 139,000), restarted the machine, loaded Access, same error message. Checked the register, the new size is 100,000. Any suggestions?

  2. Mirthrock

    I’m having this exact same issue. its seems that Windows 10 has moved these registry keys. I called Microsoft and they said that Microsoft Access is not supported via normal Office 365 support even though it is part of that product package. They told me I had to pay for a support case with Microsoft.

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