esirsock_object.dll Not Found: Rebuild the Legacy App Safely

If esirsock_object.dll is missing or cannot be loaded, repair or reinstall the old Sony Ericsson Mobile Phone Monitor or PC Suite software that owns it. esirsock_object.dll is not a Windows system file, so copying a replacement into System32 is usually the wrong fix.

What this file actually does

esirsock_object.dll is identified as the ESIrSock_object Module, a third-party application component attributed to Sony Ericsson Mobile Communications AB. It belongs to the legacy Sony Ericsson PC connectivity software family, particularly Mobile Phone Monitor and related PC Suite components.

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That software allowed older Sony Ericsson phones to communicate with Windows over a cable, infrared, or Bluetooth connection. The DLL may therefore be loaded when Windows starts the phone-management software, when a background monitor runs, or when the application detects a connected phone.

Historical file records associate it with a directory similar to:

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C:Program FilesSony EricssonMobileMobile Phone Monitor

The exact location can differ by Windows version, installation choice, and PC Suite release. The file is commonly described as a 32-bit Win32 DLL, but the available historical records contain conflicting version and size details. Those details are not useful for choosing a standalone replacement.

This file is not:

• A Windows component
• A Microsoft runtime
• A DirectX file
• A generic Visual C++ redistributable
• A DLL that Windows normally restores to System32 or SysWOW64

The parent application matters more than the DLL itself. If the old Sony Ericsson software is no longer needed, removing that software and its leftover startup entry is safer than trying to restore an isolated file.

Causes matched to symptoms

The error may be shown as:

This application failed to start because esirsock_object.dll was not found.

Other variants say that the file is missing or corrupted, that a required component is missing, or that Windows cannot load the specified module.

“Specified module could not be found” does not always mean the named file itself is absent. It can also mean that a dependency used by the DLL or its parent application cannot be loaded.

Fix 1: Identify the application that calls the DLL

Before changing files, find out which program is producing the message.

Check the error context

Note when the message appears:

1. Immediately after signing in to Windows
2. When connecting a Sony Ericsson phone
3. When opening PC Suite or Mobile Phone Monitor
4. When launching an unrelated application
5. During uninstall or reinstall

If the error names a Sony Ericsson program, proceed with application repair. If it appears for an unrelated program, do not assume that Sony Ericsson software is the correct source.

Check installed programs

On Windows 11:

1. Press Windows + I.
2. Select Apps.
3. Select Installed apps.
4. Search for Sony Ericsson, Mobile Phone Monitor, or PC Suite.
5. Select the three-dot menu beside the matching entry.
6. Choose Advanced options, Modify, Change, Repair, or Uninstall, depending on what is available.

On Windows 10:

1. Press Windows + I.
2. Select Apps.
3. Select Apps & features.
4. Search for the Sony Ericsson software.
5. Select the entry.
6. Choose Modify, Change, Repair, or Uninstall.

You can also use the older Control Panel route:

1. Press Windows + R.
2. Type appwiz.cpl.
3. Press Enter.
4. Look for Sony Ericsson PC Suite, Mobile Phone Monitor, or a related connectivity package.

If the application is listed, use its repair or change option first. Restart Windows and launch the same program that originally produced the error.

How to tell whether it worked

The repair succeeded if:

• The original Sony Ericsson application opens without the DLL message.
• The startup warning no longer appears.
• The phone-management software detects the phone as it did before.
• No new missing-DLL message replaces the original one.

If repair is unavailable or fails, continue with a complete uninstall and reinstall.

Fix 2: Reinstall the complete Sony Ericsson package

A standalone DLL is not the correct installation unit. The parent application may also need configuration files, registry entries, services, phone drivers, and other modules.

Save anything the old software contains

Before uninstalling, export or copy contacts, messages, phonebook data, and other information if the application still opens. If the phone itself contains the only copy of important data, avoid deleting the old software until you have a recovery plan.

Uninstall the damaged package

Use either of these methods:

1. Open Settings with Windows + I.
2. Go to Apps and then Installed apps on Windows 11, or Apps & features on Windows 10.
3. Select the Sony Ericsson entry.
4. Choose Uninstall.
5. Follow the package’s removal wizard.
6. Restart Windows.

If the program is not listed or its uninstaller fails:

1. Press Windows + R.
2. Enter appwiz.cpl.
3. Select the Sony Ericsson package.
4. Choose Uninstall or Change.
5. Restart after the wizard finishes.

Microsoft also provides a troubleshooter for programs that cannot be installed or removed. Use that route when an incomplete uninstall prevents a clean reinstall.

Reinstall from a trustworthy source

Use, in this order:

1. The original Sony Ericsson installation CD or supplied phone media
2. A verified OEM recovery source
3. An installer obtained from the vendor’s historical support channel
4. A preserved installer from the computer or organization that originally deployed it

No currently maintained official Sony download for this exact legacy component has been verified. Do not replace that gap with a random DLL archive.

After starting the installer:

1. Right-click the installer.
2. Select Run as administrator.
3. Accept the license and default components unless you know a custom installation is required.
4. Allow the phone-management and connectivity components to install.
5. Restart Windows.
6. Open the Sony Ericsson application before connecting the phone.
7. Connect the phone using the same connection method the software originally supported.

If the installer refuses to run, right-click it, select Properties, open the Compatibility tab, and try the Compatibility troubleshooter. You can also select an older Windows compatibility mode, enable Run this program as an administrator, select Apply, and test again. Compatibility mode is not a guarantee that the old software will work on a current Windows release.

Fix 3: Check antivirus quarantine before restoring anything

Security software may quarantine an old DLL because it is uncommon, unsigned, packed with an old installer, or located in an unusual directory. That does not prove the file is malware, and the age of the component alone is not evidence of malicious activity.

Check the security product that was active when the error began:

1. Open Windows Security from the Start menu.
2. Select Virus & threat protection.
3. Select Protection history.
4. Review entries around the time the DLL disappeared.
5. Expand any entry associated with the Sony Ericsson installation.
6. Do not restore the file automatically.
7. First confirm that the original application directory and installer are trusted.
8. Run a full scan if the file was found in an unexpected directory.

If the file was quarantined from the expected Sony Ericsson application folder and the original installation is trusted, restoring it may allow the application to start. Repair or reinstall the complete package afterward so that its files and configuration are consistent.

If the file appeared under a temporary folder, a download directory, a game folder, or another unrelated location, leave it quarantined until the program’s provenance is clear.

Fix 4: Check the application directory and architecture

A 32-bit application normally expects its private DLLs beside the application executable or in another directory configured by that application. It does not normally need you to place the file manually in a Windows system directory.

To inspect the installation:

1. Open Settings > Apps > Installed apps.
2. Find the Sony Ericsson program.
3. Open its menu and choose Advanced options if available.
4. Look for an Install location or repair option.
5. If no location is shown, right-click the program’s shortcut.
6. Select Properties.
7. Read the Target field on the Shortcut tab.
8. Open that folder in File Explorer.
9. Check whether esirsock_object.dll is beside the application executable or within the application’s own subfolders.

Do not copy the file to:

C:WindowsSystem32
C:WindowsSysWOW64

Those folders are not interchangeable storage locations for application DLLs. A misplaced copy can satisfy one lookup while causing version conflicts, permission problems, or security exposure.

If you have a 64-bit edition of Windows, that does not automatically prevent a 32-bit application from running. The relevant question is whether the legacy Sony Ericsson application and its drivers still function on the current Windows release. Reinstall the matching application package rather than mixing a 32-bit DLL with another release.

If the DLL exists in the expected folder but the message continues, the problem may be a missing dependency. Repair the parent application first. Do not assume that downloading another copy of the named file will resolve a dependency failure.

Fix 5: Repair the phone connection and its drivers

If the error appears only when a phone is connected, the application package and its connection drivers may both be involved.

Check Device Manager

1. Disconnect the phone.
2. Right-click the Start button.
3. Select Device Manager.
4. Expand Portable Devices, Modems, Universal Serial Bus controllers, and Other devices.
5. Reconnect the phone.
6. Watch for a new device, a warning icon, or an entry that appears and disappears.
7. Right-click the affected device.
8. Select Properties.
9. Read the message on the General tab and the status under Device status.

If the device has a warning icon:

1. Right-click it.
2. Select Uninstall device.
3. If offered, select the option to remove the driver package.
4. Select Uninstall.
5. Restart Windows.
6. Reinstall the original Sony Ericsson connectivity package.
7. Reconnect the phone only when the installer requests it.

Use the original cable, infrared hardware, or Bluetooth arrangement where possible. A modern replacement driver is not guaranteed to support the old Mobile Phone Monitor software.

If Device Manager reports a driver-signing, compatibility, or installation error, the problem may be the age of the package rather than esirsock_object.dll itself.

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When you manually compare driver versions across hardware, the difficult part is identifying which of many entries is actually stale and compatible with the phone. Outbyte Driver Updater can scan and show driver problems; its free scan identifies issues, while driver installation is handled by the full version. Reinstalling the Sony Ericsson package remains the definitive fix for this application-owned DLL.

Fix 6: Remove a leftover startup entry

If the error appears at every login but the Sony Ericsson program has already been removed, Windows may still be trying to start an obsolete monitor process.

Use Startup settings

1. Press Ctrl + Shift + Esc.
2. Select Startup apps in Task Manager.
3. Look for Sony Ericsson, Mobile Phone Monitor, PC Suite, or an unknown entry whose location points to the old Sony Ericsson folder.
4. Select the entry.
5. Choose Disable.
6. Restart Windows.

You can also check:

1. Open Settings.
2. Select Apps.
3. Select Startup.
4. Turn off the obsolete Sony Ericsson entry.

Do not disable an entry solely because its name is unfamiliar. Open its file location from Task Manager when available and confirm that it belongs to the removed application.

If the warning disappears after disabling the entry, uninstall the remaining Sony Ericsson software or use its own cleanup option. Do not restore the DLL merely to keep an obsolete startup item alive.

Fix 7: Use Windows repair commands only for broader corruption

SFC and DISM are designed to repair Windows components. They will not normally recreate a vendor DLL such as esirsock_object.dll.

Use them when other Windows applications also fail, Windows features are damaged, or system corruption is suspected.

1. Open the Start menu.
2. Type Command Prompt.
3. Right-click Command Prompt.
4. Select Run as administrator.
5. Run:

DISM.exe /Online /Cleanup-Image /RestoreHealth

1. Wait for it to complete.
2. Then run:

sfc /scannow

1. Restart Windows.
2. Test the Sony Ericsson application again.

Do not close the window while either scan is running. If SFC reports that it found and repaired corrupted files, restart and test. If it reports that it could not repair some files, the Sony Ericsson application still needs its own repair or reinstall.

Repeating SFC and DISM without knowing what changed can waste time while leaving the application installation untouched. Outbyte PC Repair can scan for broader Windows problems and show what it finds; the free scan identifies issues, while repair is handled by the full version. It is not a substitute for reinstalling the Sony Ericsson package that owns this DLL.

Why regsvr32 is usually the wrong fix

Do not run this as a routine repair:

regsvr32 esirsock_object.dll

regsvr32 is intended for DLLs that provide a registration entry point, commonly COM or ActiveX components. An ordinary application runtime DLL may not support self-registration.

Running the command can produce errors such as:

• The module could not be loaded
• The specified procedure could not be found
• The entry point was not found
• The module was loaded but the entry point was missing

Those messages do not repair the parent program. Use registration only if the Sony Ericsson application’s own documentation specifically requires it and identifies the correct DLL and architecture.

Is reinstalling Visual C++, DirectX, or .NET relevant?

Usually not. esirsock_object.dll is an application-owned legacy component, not a Microsoft runtime file.

Reinstall a Microsoft runtime only when the error explicitly names a runtime such as:

MSVCP*.dll
VCRUNTIME*.dll
MSVCR*.dll

A DirectX repair is similarly unrelated unless the error identifies a DirectX component. Installing unrelated runtimes can add unnecessary software without restoring the Sony Ericsson application’s files or configuration.

When uninstalling is the safest fix

Remove the old Sony Ericsson software when:

• You no longer use the phone or application.
• The error appears only at startup after the program was removed.
• No trusted installer is available.
• The package cannot run on the current Windows release.
• Reinstalling leaves repeated warnings or unstable behavior.
• The software is installed in an unexpected directory and its provenance is unclear.

Before uninstalling, preserve any data that exists only inside the old application. Then remove it through Settings > Apps or Control Panel > Programs and Features, restart Windows, and disable any remaining startup item.

Sony’s current Xperia Companion is a different product and should not be treated as a guaranteed replacement for the old Sony Ericsson Mobile Phone Monitor software.

Last resort: System Restore or an isolated older environment

System Restore can roll back system settings and installed-program changes to an earlier restore point. It is useful when the DLL disappeared immediately after a recent installation or removal, but it is not a substitute for reinstalling the owning application.

To check recovery options:

1. Open the Start menu.
2. Type Recovery.
3. Select Recovery or Recovery options.
4. Choose Open System Restore if it is available.
5. Select a restore point from before the problem began.
6. Review the affected programs.
7. Start the restore only after backing up current work.

If the legacy program is essential but cannot run reliably on Windows 11 or Windows 10, use a suitably isolated older Windows environment with appropriate backups and limited network exposure. There is no verified basis for promising that the original Sony Ericsson package will work on a particular current Windows release.

Frequently asked questions

Is esirsock_object.dll a Windows file?

No. Available evidence identifies it as a Sony Ericsson application DLL associated with the ESIrSock_object Module and Mobile Phone Monitor software family.

Can I download just this DLL?

Do not download it from a random DLL website. A file may contain malware, belong to the wrong release, use the wrong architecture, or fail because another dependency is missing. Restore the complete Sony Ericsson application from original media or a verified vendor-provided installer instead.

Should I put it in System32?

No. Keep application DLLs in the directory used by their owning program. Manually placing this file in a Windows directory can create conflicts and does not repair the application installation.

Why does the error say the specified module cannot be found when the file is present?

The named DLL may depend on another missing or unloadable component. Check the parent executable, application architecture, permissions, drivers, and the complete installation.

Will reinstalling Visual C++ fix it?

Usually no. Reinstalling a runtime is relevant only when Windows names a Microsoft runtime DLL such as MSVCP, MSVCR, or VCRUNTIME.

Should I register the file with regsvr32?

Not as a general fix. Registration applies to DLLs designed to expose a registration entry point, and this application DLL should normally be restored through its parent package.

What if the error appears only at login?

Look for a leftover Sony Ericsson startup item or service. Disable it through Task Manager > Startup apps or Settings > Apps > Startup, then uninstall the obsolete package if it is no longer needed.

Is the file malware because it is old?

Not necessarily. Check its location, digital-signature information where available, antivirus results, and the application that installed it. An unexpected copy outside the Sony Ericsson application directory deserves more investigation than a file restored by a trusted installation.

What is the best fix on Windows 11 or Windows 10?

Identify the calling program, repair or reinstall the complete Sony Ericsson package, and test the connection. If the software is obsolete or incompatible, preserve your data and remove it rather than forcing a standalone DLL into Windows.

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