“a0001735.dll was not found.” The a0001735.dll error usually points to an old IIS Classic ASP component, but the filename is not confirmed as a current official Windows filename.
Do not begin by downloading the DLL. First identify which program requested it, then repair that program or the Windows feature it actually uses.
Which fix applies to you
Use this list to choose the right path:
- An old website or local IIS server fails: install or repair the IIS ASP feature.
- A legacy application, installer, or game requests the file: repair or reinstall that application from its original source.
- The problem started after antivirus activity or malware removal: inspect quarantine and security history before restoring anything.
- Windows reports several missing or damaged components: run DISM, then SFC.
- The message says “not designed to run on Windows”: suspect corruption, the wrong architecture, or an invalid renamed file.
- The message says “specified module could not be found”: a dependency may be missing even if
a0001735.dllexists. - You found the file in a temporary, downloads, startup, or user-writable folder: treat it as suspicious until verified.
- The error appears after an update or disk problem: check Windows repair status and the affected application before replacing files.
What is a0001735.dll
The file is described as Active Server Pages and is associated with Microsoft Internet Information Services, or IIS. Classic ASP is an IIS server-side scripting environment used by older websites and applications.
The important qualification is that Microsoft documentation identifies the IIS Classic ASP handler as:
Recommended Free Tools
#1 Best Overall
- Does Not Fix Hardware Issues - Please Test Your PC hardware to be sure everything passes before buying this USB Windows 11 Software Recovery USB.
- Make sure your PC is set to the default UEFI Boot mode, in your BIOS Setup menu. Most all PC made after 2013 come with UEFI set up and enabled by Default
- Does Not Include A KEY CODE, LICENSE OR A COA. Use your Windows KEY to preform the REINSTALLATION option
- Free tech support
%windir%system32inetsrvasp.dll
Microsoft documentation for Windows XP-era IIS also refers to Asp51.dll. It does not establish a0001735.dll as a normal current Windows filename.
That means a0001735.dll may be:
- A renamed or archived copy of an older IIS Classic ASP binary.
- A stale reference left by Windows XP-era software.
- A file renamed during backup, quarantine, restoration, or malware cleanup.
- A third-party file using Microsoft-like metadata.
- A dependency requested by an old application rather than by IIS itself.
Do not assume that a file described as “Active Server Pages” belongs in System32 or SysWOW64. Filename, description, and publisher fields alone do not prove authenticity.
Microsoft’s explanation of Classic ASP and its IIS modules is available in the Classic ASP overview.
Find the program requesting the DLL
The requesting program determines the correct repair. Reinstalling IIS will not fix an unrelated legacy application that happens to ask for this filename.
Check when the error appears
Note whether the message appears when you:
- Start Windows.
- Launch a specific program or game.
- Run an installer.
- Start IIS or an old website.
- Open a document or shortcut.
- Log in after antivirus or cleanup software ran.
If the error appears with one application, close it and use that application’s repair or reinstall option first.
Check the event details
Open Event Viewer:
- Press Windows and type Event Viewer.
- Open Event Viewer.
- Expand Windows Logs.
- Select Application.
- Look for an error at the time the message appeared.
- Open the event and record the faulting application, module, and full message.
For IIS failures, also check:
- Open Event Viewer.
- Expand Applications and Services Logs.
- Check Microsoft, Windows, and IIS-related logs available on the system.
- Compare the timestamp with the failed request.
Also inspect the shortcut or service that starts the affected program. Right-click a shortcut, select Properties, and check Target. For a service, press Windows, type Services, open it, and inspect the service’s executable information if available.
Record the full path, Windows version, whether Windows is 32-bit or 64-bit, and the exact error text. This evidence prevents replacing the wrong file.
Fix 1: Repair the application that requests the file
This is the safest first fix when the message belongs to one legacy program, installer, or game.
Outdated Drivers Are Slowing You Down
One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallUse the installed-app repair option
On Windows 11:
- Open Settings.
- Select Apps.
- Select Installed apps.
- Find the affected application.
- Select the three-dot menu.
- Choose Advanced options, if available.
- Select Repair.
- Start the application again.
On Windows 10:
- Open Settings.
- Select Apps.
- Select Apps & features.
- Choose the affected application.
- Select Advanced options.
- Select Repair, if available.
If there is no repair option, use the application’s original installer and select Repair when offered. For a game or packaged application, use its official launcher verification or repair function.
Rank #2
- Video Link to instructions and Free support VIA Amazon
- Great Support fast responce
- 15 plus years of experiance
- Key is included
If repair does not help, uninstall the application, restart Windows, and reinstall it from its original installer or official Microsoft distribution channel. Do not preserve a suspicious DLL from the old installation unless you have verified its source and signature.
How to tell whether this worked
The repair succeeded if the application starts without requesting a0001735.dll, or if the original installer completes normally. If the same message returns, note the exact executable named in the error and continue with the IIS and security checks below.
Fix 2: Install the IIS Classic ASP feature
Use this fix only when the affected machine actually hosts an old ASP website or an application that depends on IIS Classic ASP.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Installing ASP.NET does not install Classic ASP. The IIS feature you need is named ASP under Application Development.
Windows 11 and Windows 10
- Press Windows, type Turn Windows features on or off, and open it.
- Expand Internet Information Services.
- Expand World Wide Web Services.
- Expand Application Development Features.
- Select ASP.
- Leave the required supporting features selected.
- Select OK.
- Allow Windows to install the components.
- Restart Windows if prompted.
- Test the old website or application again.
If IIS is not listed, open Settings, select System, then Optional features and More Windows features, depending on the Windows build. You can also search for IIS from the Start menu and open the Windows Features dialog.
Microsoft documents the ASP feature and its required ISAPI extensions in the IIS ASP configuration documentation.
Windows Server
On Windows Server:
- Open Server Manager.
- Select Manage.
- Select Add Roles and Features.
- Choose Role-based or feature-based installation.
- Select the target server.
- Expand Web Server (IIS).
- Expand Web Server.
- Expand Application Development.
- Select ASP.
- Continue through the wizard and select Install.
- Restart if requested.
- Test the IIS site.
If the ASP feature is already selected, remove and add it only as a controlled troubleshooting step, preferably after recording the current IIS configuration.
Free tools Windows power users keep installed
One-click scans. No signup required.
Confirm the IIS files
Microsoft documents the standard IIS ASP handler as:
%windir%system32inetsrvasp.dll
To check the folder:
- Press Windows+R.
- Enter:
%windir%system32inetsrv
- Select Enter.
- Look for
asp.dll.
The presence of asp.dll does not prove that every IIS configuration problem is resolved, and its absence does not justify downloading a0001735.dll. Repair the Windows feature instead.
Rank #3
- Less chaos, more calm. The refreshed design of Windows 11 enables you to do what you want effortlessly.
- Biometric logins. Encrypted authentication. And, of course, advanced antivirus defenses. Everything you need, plus more, to protect you against the latest cyberthreats.
- Make the most of your screen space with snap layouts, desktops, and seamless redocking.
- Widgets makes staying up-to-date with the content you love and the news you care about, simple.
- Stay in touch with friends and family with Microsoft Teams, which can be seamlessly integrated into your taskbar. (1)
Fix 3: Repair Windows component corruption
Use this path when multiple Windows components are failing, the problem followed an interrupted update, or IIS installation itself reports errors.
Open an elevated Command Prompt:
- Press Windows.
- Type Command Prompt.
- Right-click Command Prompt.
- Select Run as administrator.
- Select Yes at the permission prompt.
Run DISM first:
DISM /Online /Cleanup-Image /RestoreHealth
Wait for it to finish. Then run System File Checker:
sfc /scannow
Restart Windows after both commands complete.
Microsoft recommends using DISM before SFC because DISM can repair the component source used by Windows. See Microsoft’s System File Checker repair instructions.
Outbyte PC Repair can reduce the manual work of hunting through repair results and repeating SFC or DISM without knowing what changed; its free scan shows detected issues, while repair is performed by the full version. It is optional, and an application-specific DLL problem still requires repairing or reinstalling that application.
Interpret the results
- “Windows Resource Protection did not find any integrity violations” means SFC found no protected-system corruption. Investigate the requesting application, IIS configuration, dependencies, or security history.
- SFC repaired files successfully: restart and test again.
- SFC could not repair some files: run DISM again, restart, and repeat SFC. If the issue remains, use Windows recovery or repair installation methods appropriate to your edition.
- DISM cannot find source files: Windows may need a matching repair source or installation media. Do not substitute a random DLL.
SFC and DISM repair protected Windows components. They are not guaranteed to recreate an arbitrary file named a0001735.dll.
Fix 4: Check antivirus quarantine and malware history
A filename beginning with a0001735 may have been renamed by software, restored from a backup, or left behind after malware cleanup. Do not restore it automatically.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Review Windows Security
- Open Windows Security.
- Select Virus & threat protection.
- Select Protection history.
- Review detections and quarantined items around the time the error began.
- Open the relevant entry and record the original path and detection name.
Restore a quarantined file only when all of these conditions apply:
- The original path was a legitimate IIS or application directory.
- The file has a valid Microsoft digital signature.
- The affected installation is known and trusted.
- A security scan found no continuing infection.
To check a signature:
- Right-click the file.
- Select Properties.
- Open Digital Signatures.
- Select the signer.
- Select Details.
- Confirm that Windows reports the signature as valid.
A copy in a temporary folder, Downloads folder, user profile, startup directory, or random restore-point location should not be trusted merely because its metadata says Microsoft.
If malware is suspected, leave the file quarantined, update Windows Security, and run a full scan. Use an offline scan when Windows Security recommends it. Then reinstall the affected IIS feature or application from trusted media.
Fix 5: Check architecture and dependency errors
Third-party listings associate a0001735.dll with an old 32-bit IIS-era binary. That does not make it suitable for a current 64-bit Windows installation.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Rank #4
- Video Link to instructions and Free support VIA Amazon
- Great Support fast responce
- 15 plus years of experiance
- Key is included
On 64-bit Windows:
System32normally contains 64-bit system components.SysWOW64contains 32-bit system components.
Do not copy a file between these folders indiscriminately. A 32-bit caller may require a 32-bit dependency, while a 64-bit caller may require a 64-bit dependency. Installing the matching Windows feature or application package is safer than choosing a folder manually.
“Not designed to run on Windows”
This wording commonly indicates one of the following:
- The file is corrupted.
- The file is not a valid DLL.
- The file has the wrong architecture.
- A renamed file is being loaded by the wrong program.
- A required dependency is incompatible.
Repair the application or IIS feature, then run DISM and SFC. Do not force registration or replace the file with an archive download.
“The specified module could not be found”
This message can mean that a dependency of the named DLL is missing. The named file may exist while another required module does not.
Check the application’s official repair documentation, Event Viewer, and installation logs. Avoid deleting or replacing unrelated DLLs because that can create additional startup failures.
Do not use regsvr32 for this problem
regsvr32 is for DLLs that expose COM registration entry points such as DllRegisterServer. It is not a general DLL installation command.
Do not run:
regsvr32 a0001735.dll
There is no evidence that the IIS ASP engine should be repaired this way. Registration will not restore IIS feature configuration, dependencies, permissions, or the correct architecture. A failed command can add a second error and obscure the original problem.
Microsoft documents the command’s actual scope in the regsvr32 reference.
Do not download or manually copy the DLL
Random DLL download sites can provide malware, an altered file, the wrong architecture, or a file from an incompatible Windows build. Even a clean copy may not fix the application because the real issue is a missing IIS feature, dependency, registry configuration, permission, or application installation.
Best Value
- COMPATIBILITY: Designed for both Windows 11 Professional and Home editions, this 16GB USB drive provides essential system recovery and repair tools
- FUNCTIONALITY: Helps resolve common issues like slow performance, Windows not loading, black screens, or blue screens through repair and recovery options
- BOOT SUPPORT: UEFI-compliant drive ensures proper system booting across various computer makes and models with 64-bit architecture
- COMPLETE PACKAGE: Includes detailed instructions for system recovery, repair procedures, and proper boot setup for different computer configurations
- RECOVERY FEATURES: Offers multiple recovery options including system repair, fresh installation, system restore, and data recovery tools for Windows 11
Do not copy a0001735.dll into:
C:WindowsSystem32C:WindowsSysWOW64- The IIS directory
- An application’s folder
The normal repair sources are:
- The ASP feature in Windows Features or Server Manager.
- The affected application’s original installer.
- Windows component repair using DISM and SFC.
- A trusted backup from the exact system and application installation, used only in a controlled recovery situation.
Windows XP and Server 2003-era files should not be transplanted into current Windows installations.
Fix 6: Update or reinstall related drivers only when evidence points there
Drivers are not the normal cause of an IIS Classic ASP DLL error. Consider this path only when the same failure began after a graphics, storage, chipset, or security-device driver change and Event Viewer identifies that driver or device.
Check Device Manager
- Right-click Start.
- Select Device Manager.
- Expand the device category connected to the failure.
- Right-click the device.
- Select Properties.
- Open the Driver tab.
- Record the provider, date, and version.
- Use Update Driver or Uninstall Device only when the device is clearly involved.
- Restart Windows.
For a clean driver repair, download the matching driver from the computer or device manufacturer, or use Windows Update. Do not install a driver merely because a DLL error appeared.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errorsOutbyte Driver Updater can reduce the work of identifying which of many installed drivers is stale; its free scan identifies detected driver issues, while installation is handled by the full version. It is optional and is not a substitute for repairing IIS or reinstalling the program that requests this DLL.
Prevention after the repair
Once the error is resolved:
- Keep Windows updated.
- Keep IIS and Classic ASP enabled only when the workload requires them.
- Remove abandoned legacy applications and IIS sites.
- Maintain backups of working application installers and IIS configuration.
- Keep antivirus protection enabled.
- Avoid DLL download websites and registry-cleaner utilities.
- Record the exact application and path whenever a DLL error appears.
- Do not move system DLLs between
System32andSysWOW64.
Evidence to collect if the error returns
Before making another change, record:
- The complete error text.
- The executable that triggers it.
- The requested file path.
- The path where any copy of
a0001735.dllwas found. - Windows edition and version.
- 32-bit or 64-bit architecture.
- Whether IIS and the ASP feature are installed.
- Event Viewer entries from the same time.
- Antivirus quarantine or protection history.
- Results from DISM and SFC.
- Whether the problem began after an update, cleanup, disk failure, application removal, or malware incident.
This information distinguishes an IIS configuration problem from a legacy application, missing dependency, wrong architecture, or suspicious renamed file.
FAQ
Is a0001735.dll an official Windows 11 DLL?
Microsoft documentation does not confirm a0001735.dll as a current official Windows filename. Microsoft documents the IIS ASP handler as asp.dll and refers to Asp51.dll in Windows XP-era security material.
Should I download a0001735.dll?
No. Downloading an unverified DLL can introduce malware or an incompatible file and often leaves the underlying IIS or application problem unresolved.
Is this the same as ASP.NET?
No. Classic ASP and ASP.NET are different IIS features. Select ASP under Application Development Features when repairing Classic ASP.
Will reinstalling IIS always fix the error?
No. Reinstalling IIS helps when IIS or Classic ASP is the component making the request. It will not repair an unrelated application that uses a stale filename or has its own missing dependency.
Should I register the file with regsvr32?
No. regsvr32 is not a general DLL repair command, and there is no evidence that this IIS handler should be manually registered.
What if the file exists but Windows still reports it as missing?
The message may refer to a missing dependency, an inaccessible path, a wrong architecture, or a corrupted file. Check the requesting executable and Event Viewer instead of copying the file elsewhere.
Can SFC restore this exact filename?
Not necessarily. SFC repairs protected Windows components. It does not guarantee restoration of a renamed, third-party, or application-specific file called a0001735.dll.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
