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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware match“ The program can’t start because msltus35.dll is missing from your computer.”
You may instead see “This application failed to start because msltus35.dll was not found,” “Error loading msltus35.dll,” or Access-style “Couldn’t find installable ISAM.” The exact wording varies, but msltus35.dll is a legacy Microsoft Jet database component, not a normal Windows 10 or Windows 11 system file.
The safest repair is usually to identify the old application that needs Jet 3.5, then repair or reinstall that application from its original, trusted installer.
Which fix applies to you
Use this list to choose the shortest safe path:
- The error appeared after reinstalling an old business program, Access database, or Visual Basic application: repair or reinstall that program first.
- The error started after removing or changing Microsoft Office: repair the remaining Office installation, or reinstall the application’s original database components.
- Windows Security quarantined the file: inspect Protection history and restore it only if the originating installer is trusted and the file can be verified.
- The program is 32-bit on 64-bit Windows: confirm that the application and Jet components use the same architecture. Do not copy the DLL into random system folders.
- The file exists but the program reports “installable ISAM”: the file may be unregistered, incompatible, or missing a dependency. Conditional
regsvr32repair may apply. - The program is no longer supported: use the original vendor installer, a supported replacement, or an isolated virtual machine.
- You believe Windows itself is damaged: run DISM followed by SFC, but do not expect those commands to recreate an obsolete Jet file that was never part of the current Windows image.
- You are considering a DLL download site: stop. An isolated download can contain malware, use the wrong architecture, or fail because the rest of Jet is missing.
What msltus35.dll is
msltus35.dll is the Microsoft Jet Lotus 1-2-3 installable ISAM driver. Jet used ISAM components to read and write external database formats. In this case, the driver provided Lotus 1-2-3 file support.
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Jet 3.5 and Jet 3.51 were used by older Microsoft and third-party software, including:
- Microsoft Access 97-era applications
- Visual Basic 5 and Visual Basic 6 database programs
- DAO-based business software
- Legacy applications that import or export Lotus 1-2-3 files
- Programs that depend on the older Jet database engine
It is not a graphics library, game runtime, Visual C++ redistributable, DirectX component, or .NET file. It is also not a current Windows component that every Windows 10 or Windows 11 installation should contain.
Microsoft’s historical Jet component documentation identifies MSLTUS35.DLL as the external Lotus ISAM driver. The same documentation lists related Jet files such as MSJET35.DLL, MSJINT35.DLL, and MSJTER35.DLL, which explains why replacing only one DLL often does not repair the application.
Historical Jet documentation records different file versions for Jet 3.5 and Jet 3.51. There is no single universal version that should be copied to every computer.
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1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsWhy the error appears now
The file can become unavailable even when the application worked previously. Common triggers include:
- An old application was copied to a new computer instead of properly installed.
- A repair or uninstall removed part of Office, Access, DAO, or Jet.
- The original installer was interrupted.
- Antivirus software quarantined a legacy component.
- A Jet registration entry was damaged.
- A 32-bit program is being repaired with 64-bit components.
- A dependency of
msltus35.dllis missing. - The application is fundamentally incompatible with current Windows.
The message does not always prove that the file itself is absent. “The specified module could not be found” can mean that Windows found msltus35.dll but could not load one of its dependencies.
Before changing files, identify the exact executable that produces the message. Check the shortcut’s Properties, the program’s installation folder, its documentation, and any vendor support information. The application’s name is more useful than the DLL filename when choosing a repair.
Fix 1: Repair the application that reports the error
This is the most likely successful fix because Jet components normally arrive as part of an application or its database-access feature.
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- Open Start.
- Select Settings.
- Select Apps.
- Select Installed apps.
- Find the program that reports the error.
- Select its three-dot menu.
- Choose Advanced options, if available.
- Select Repair.
- Start the program again and test the database function that previously failed.
If Repair is unavailable, use the program’s original installer or the classic Control Panel path:
- Press Windows key + R.
- Type
appwiz.cpl. - Press Enter.
- Select the affected program.
- Choose Change, Repair, or Modify.
- Select the database, data-access, or complete-installation option if the installer provides one.
- Restart Windows and test the program.
If the program was merely copied from another computer, uninstall that copy and run its authentic installer. Copying the program folder does not install Jet registration, dependencies, or database providers.
Repair Microsoft Office
If the affected application is Access or depends on an Office installation:
- Open Settings.
- Select Apps.
- Select Installed apps.
- Find the Microsoft Office or Microsoft 365 installation.
- Select the three-dot menu.
- Choose Modify.
- Select Quick Repair, then choose Repair.
- If the problem remains, repeat the process and choose Online Repair.
- Restart Windows and test Access or the dependent application.
Online Repair is more comprehensive and may require the Office installation to download files again. If the old program specifically requires Jet 3.5, repairing a modern Office installation may not install that historical component. In that situation, use the original application installer or a vendor-preserved Jet installer rather than substituting a newer database engine.
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If repair does not restore the program, perform a complete reinstall.
- Back up the program’s databases, templates, configuration files, and license information.
- Open Settings → Apps → Installed apps.
- Select the affected application.
- Choose Uninstall.
- Restart Windows.
- Sign in with an administrator account.
- Run the original installer using Run as administrator.
- Choose a complete installation, including database support, DAO, Jet, or Lotus import/export features when offered.
- Restart Windows again.
- Open the program and test its normal database operation.
For Access 97, Visual Basic-era software, or another program that explicitly requires Jet 3.51, use authentic installation media or a verifiable Microsoft archive package. Historical package names include Jet35upd.exe and Jet35sp3.exe, but these are legacy references, not current supported Windows redistributables.
Do not replace Jet 3.5 with Jet 4.0, ACE, or MDAC simply because those names contain “Jet” or “data access.” A program hard-coded for Jet 3.5 may not recognize a newer provider.
Fix 3: Check whether Windows Security quarantined the file
A security product may remove an old database component if it is damaged, unsigned, or flagged by a detection rule.
- Open Start.
- Type Windows Security.
- Open the app.
- Select Virus & threat protection.
- Select Protection history.
- Open the event associated with the affected application or
msltus35.dll. - Review the file path, detection name, and source.
- Restore or allow the file only if it came from a trusted installer and its source can be verified.
- Reinstall the application if the file was removed from an untrusted or unknown location.
Do not disable antivirus protection just to force an old DLL to load. If the installer is not trustworthy, obtain the program from its original vendor, organization, or installation media instead.
Fix 4: Confirm the 32-bit architecture
msltus35.dll is a 32-bit Jet 3.5 component. A 32-bit application can run on 64-bit Windows through WOW64, but a 64-bit application cannot load a 32-bit DLL.
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Check the affected program’s documentation or installation folder. Older applications commonly install under C:Program Files (x86), although folder location alone is not conclusive.
On 64-bit Windows:
System32normally contains native 64-bit system files.SysWOW64normally contains 32-bit system components used by 32-bit processes.- A 32-bit program should load compatible 32-bit Jet components.
- A 64-bit program cannot be fixed by placing a 32-bit DLL beside its executable.
Do not copy msltus35.dll manually into System32, SysWOW64, or the application folder. That can hide the original installation problem, create version conflicts, and introduce an unsafe file.
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If the program is 32-bit but the installer added only 64-bit database components, uninstall the incorrect installation and reinstall the application’s supported 32-bit database components. Mixing 32-bit and 64-bit Office, DAO, Jet, and ACE providers can produce additional provider or registration errors.
Fix 5: Test whether registration is damaged
regsvr32 is not a universal repair command for DLL errors. It can be relevant to historical Jet 3.5 installable ISAM components, but only when the file is the correct architecture, is self-registering, and has its dependent Jet files available.
First confirm that the file came from a trusted installation. Do not download it solely to run this command.
On 64-bit Windows, a typical command for a 32-bit component is:
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"%windir%SysWOW64regsvr32.exe" "%windir%SysWOW64msltus35.dll"
To run it:
- Open Start.
- Type Command Prompt.
- Right-click Command Prompt.
- Select Run as administrator.
- Enter the command.
- Press Enter.
- Read the result instead of assuming registration succeeded.
- Restart the affected application.
On 32-bit Windows, the applicable registration tool is normally:
"%windir%System32regsvr32.exe" "%windir%System32msltus35.dll"
If the file is installed in the application’s own directory, use its verified path rather than copying it elsewhere.
A message about a missing entry point, missing module, or registration failure usually means the file is incompatible, incomplete, not self-registering, or missing a dependency. Reinstall the complete Jet-dependent application instead of repeatedly running regsvr32.
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Fix 6: Repair Windows component corruption with DISM and SFC
DISM and SFC repair Windows component corruption. They do not normally recreate msltus35.dll, because Jet 3.5 is not generally part of the current Windows image.
Run DISM first:
- Open Start.
- Type Command Prompt.
- Right-click it.
- Select Run as administrator.
- Run:
DISM.exe /Online /Cleanup-Image /RestoreHealth
- Wait for the command to finish.
- Restart Windows if requested.
- Open an elevated Command Prompt again.
- Run:
sfc /scannow
- Restart Windows.
- Test the affected application.
If SFC reports that it repaired files, test the program again. If both commands complete without resolving the error, return to the application repair or reinstall steps. Do not keep repeating SFC and DISM when the missing component belongs to an old application rather than Windows.
When manually checking Windows corruption and tracking what changed becomes tedious, Outbyte PC Repair can scan for reported system issues; its free scan identifies findings, while repair is performed by the full version. It is optional, and reinstalling the Jet-dependent application remains the definitive fix for an application-specific missing file.
Fix 7: Check Windows Update and device drivers only when relevant
A graphics, sound, chipset, or storage driver does not normally install msltus35.dll. Device Manager is therefore not a direct fix for this Jet error. Use it only if the application also fails because of a separate hardware or compatibility problem.
To check Windows Update:
- Open Settings.
- Select Windows Update.
- Select Check for updates.
- Install available updates.
- Restart Windows.
To inspect a device driver:
- Right-click Start.
- Select Device Manager.
- Expand the relevant category.
- Right-click the device.
- Select Properties.
- Open the Driver tab.
- Review the provider and status.
- Use Update Driver only with a driver supplied through Windows Update or the device manufacturer.
- Restart Windows if a driver changes.
A driver update will not supply the Jet ISAM file. It is relevant only when the legacy application has an additional hardware dependency.
When manually checking each device and hunting through driver versions is the problem, Outbyte Driver Updater can scan for reported driver issues; its free scan shows what it finds, while driver installation is handled by the full version. It is optional and does not replace reinstalling the application that requires msltus35.dll.
Fix 8: Use a controlled environment for obsolete software
Some Jet 3.5 applications cannot run reliably on current Windows, even after the missing file is restored. This is especially likely when the program depends on old installers, 16-bit setup components, obsolete Office versions, or unsupported database providers.
Safer options include:
- A supported replacement application
- An update from the original software vendor
- A virtual machine containing the required legacy environment
- A dedicated older computer isolated from sensitive networks
- An exported database opened with a supported modern application
Keep legacy software isolated when it handles sensitive business data. Do not connect an unsupported environment to unnecessary network resources, and do not use random DLL sites to make it appear modern.
System Restore is appropriate only if a restore point predates the failure and the file was previously present:
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- Open Start.
- Type Recovery.
- Open Recovery Control Panel.
- Select Open System Restore.
- Choose a restore point from before the problem.
- Review affected programs.
- Start the restore and test the application afterward.
System Restore cannot install Jet 3.5 on a computer that never had the component.
What not to do
Avoid these common but unreliable repairs:
- Downloading
msltus35.dllfrom a generic DLL repository - Copying an unknown DLL into
System32 - Copying a 32-bit DLL into a 64-bit application
- Running
regsvr32against every DLL error - Installing MDAC 2.8 as if it were a guaranteed Jet 3.5 installer
- Installing a modern Access Database Engine without checking application compatibility
- Disabling antivirus protection permanently
- Assuming SFC or DISM can restore every third-party file
- Replacing the DLL without reinstalling its related Jet components
A standalone file may have the wrong version, architecture, dependencies, or provenance. It can also leave the application’s registration and database configuration broken.
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FAQ
Is msltus35.dll included with Windows 11 or Windows 10?
No. Current Windows installations should not be expected to contain this legacy Jet 3.5 Lotus ISAM driver. It normally comes from an old application, Office or Access component, or a compatible database installation.
Does the file support Lotus 1-2-3?
Yes. It is the Jet installable ISAM driver for Lotus 1-2-3 formats. The application may still need it even when the user no longer directly opens Lotus files, because the program’s database layer may load all configured Jet drivers.
Why does an Access application report “Couldn’t find installable ISAM”?
The Jet installation may be incomplete, the required ISAM registration may be damaged, the application may be using the wrong architecture, or a dependency may be missing. The message does not necessarily mean that only msltus35.dll needs to be replaced.
Does MDAC install this file?
Do not treat MDAC as a guaranteed msltus35.dll installer. MDAC is a broader, historical data-access stack, and its packages target old Windows environments. Use the application’s original Jet-dependent installer instead.
Should I use System32 or SysWOW64?
Do not manually copy the DLL to either directory. On 64-bit Windows, a 32-bit process normally uses the WOW64 file-system layout, where SysWOW64 contains 32-bit system components. The correct repair is to install the complete, matching application components.
Can a 64-bit application use this DLL?
No. A 64-bit process cannot load this 32-bit Jet component. The application must use a compatible 32-bit process or be replaced or upgraded.
When should I use regsvr32?
Only after confirming that the file is a trusted, compatible Jet component and that registration is appropriate. Use the registration tool matching the DLL architecture. If registration reports a missing dependency or entry point, reinstall the complete Jet-dependent application.
What if the file keeps disappearing?
Check Windows Security → Virus & threat protection → Protection history, then inspect the application’s installation logs and permissions. If every reinstall triggers the same issue, verify the installer source and contact the application vendor. A clean boot or separate Windows user profile can help distinguish a system-wide problem from per-user configuration damage.
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