Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →A message naming MSVCP140.dll or VCRUNTIME140.dll normally means the application cannot find a matching Microsoft Visual C++ Redistributable. Install or repair the official runtime with the same architecture as the application. If the message is E1696: cannot open source file "ctype.h" inside Visual Studio, install or repair the C++ workload and Windows SDK instead; that is a development-environment problem, not a missing launch-time DLL.
First identify which kind of “C++ missing” error you have
Windows uses “C++ missing” to describe two unrelated failures. The correct fix depends on whether an already-built program will not start or a C++ project cannot find a header while you are editing or compiling it.
As an Amazon Associate I earn from qualifying purchases.
| What you see | When it appears | What is usually missing | Correct remedy |
|---|---|---|---|
A dialog names MSVCP140.dll, VCRUNTIME140.dll, or a similar runtime DLL. |
When launching an installed application or game. | The Microsoft Visual C++ runtime, a damaged installation, or the wrong CPU architecture. | Install or repair the matching Visual C++ Redistributable, then check for a legacy runtime if the vendor requires one. |
E1696: cannot open source file "ctype.h" or another standard-header error. |
In Visual Studio or its editor. | The Universal C Runtime (UCRT) files supplied by a Windows SDK, or an incorrect project/IntelliSense configuration. | Use Visual Studio Installer to add or repair C++ tools and a Windows SDK, select that SDK in the project, and rebuild. |
A real build reports a C#### compiler diagnostic. |
During compilation. | An actual compiler include-path, SDK, or source problem. | Fix the component or project setting identified by the compiler; do not treat it as an editor-only warning. |
The distinction matters because installing a runtime cannot supply ctype.h to Visual Studio, and adding a Windows SDK will not repair a broken runtime for an unrelated application.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Why launch-time programs report a missing C++ DLL
Applications built with Microsoft Visual C++ do not normally include every C and C++ library inside their own executable. They use shared runtime libraries installed in Windows. The Microsoft Visual C++ Redistributable supplies those libraries. If the required package is absent, damaged, or built for another architecture, Windows can display a missing-DLL dialog before the application opens.
#1 Best Overall
The filename is a useful clue. MSVCP140.dll is part of the C++ standard-library runtime, while VCRUNTIME140.dll is part of the Visual C++ runtime. A related filename does not prove that one particular package is required, so record the complete message and the application’s documentation before installing anything.
Microsoft recommends the latest supported v14 runtime for applications built with Visual Studio 2017 through 2026. The current v14 distribution is offered in x86, x64, and ARM64 forms and supports Windows 10 and Windows 11. The architecture still has to match the application that is failing.
Fix a missing MSVCP140.dll or VCRUNTIME140.dll at application launch
1. Record the exact error and application architecture
- Write down the complete DLL filename, including any suffix or number.
- Check the application’s system requirements or vendor support page for whether it is 32-bit (x86), 64-bit (x64), or ARM64.
- Do not infer the required package from the architecture of Windows alone. A 32-bit application running on 64-bit Windows needs the x86 redistributable.
If the dialog names a different runtime generation, keep that information. An application built for an older toolset may need its older redistributable even when the current v14 package is installed.
2. Download the official redistributable
Open Microsoft’s Latest Supported Visual C++ Redistributable Downloads page. Choose the package whose architecture matches the application: x86 for a 32-bit program, x64 for a 64-bit program, or ARM64 for a native ARM64 program. Use Microsoft’s installer rather than a loose DLL downloaded from a file mirror.
On a 64-bit Windows computer, it is common for several applications to use different architectures. If you use both 32-bit and 64-bit programs that show runtime errors, install the corresponding x86 and x64 packages. Installing both does not convert one architecture into the other; each application loads the libraries for its own process.
3. Install the package
- Close the affected application and any installer that might be using it.
- Run the downloaded Microsoft redistributable installer.
- Accept the license terms and allow the installer to complete.
- If Windows asks for administrator approval, provide it through the normal User Account Control prompt.
- Restart the application. A full Windows restart is also reasonable when the installer requests it or the program remains locked in memory.
The redistributable is a shared prerequisite. Installing it does not replace the application, alter its project files, or provide Visual Studio’s headers and compiler.
4. Repair an installation that is already present
A package can appear installed while one of its files is damaged or missing. Open Settings → Apps → Installed apps on Windows 11, or the equivalent Installed apps page on Windows 10. Find the Microsoft Visual C++ Redistributable entry that corresponds to the needed architecture, open its menu, choose Modify, and select Repair when that option is offered. Follow the installer to completion and retry the application.
If no repair option is available, run the official installer again. It will normally offer to repair or reinstall the existing package. Do not delete individual DLL files from system folders as a substitute for repairing the package.
5. Check for a legacy dependency
The latest v14 runtime covers applications built with Visual Studio 2017–2026, but older applications can depend on an earlier generation such as Visual C++ 2013 or 2010. Older redistributables remain side by side; installing v14 does not always replace them. Consult the application vendor’s requirements for the specific legacy version and install that version from Microsoft if required.
Install only the architecture and version the application needs. If the vendor lists more than one prerequisite, each may be required because separate programs can use separate runtime generations.
Why downloading a single DLL is the wrong fix
DLL-mirror sites distribute individual files without the package servicing, version relationship, or provenance that the application expects. A file with the right name can still be the wrong build or architecture, and manually copying it can create a new error or leave the redistributable installation inconsistent. The supported approach is to install or repair the complete Microsoft package that owns the file.
Do not replace a system DLL by copying one from another computer, changing file permissions, or placing it beside the executable unless the application vendor explicitly documents a private runtime deployment. Those actions make later updates and diagnosis harder.
Fix “cannot open source file ctype.h” in Visual Studio
ctype.h is a standard C header supplied through the Universal C Runtime (UCRT) component of the Windows SDK. On a typical installation, it is under C:Program Files (x86)Windows Kits10Include<SDK version>ucrt. The exact SDK-version folder varies, so do not type a version from another computer.
1. Add the C++ workload and SDK in Visual Studio Installer
- Close Visual Studio.
- Open Visual Studio Installer from the Start menu.
- Find the installed Visual Studio instance and choose Modify.
- On the Workloads tab, select Desktop development with C++.
- In the workload’s individual components, ensure the MSVC build tools and a Windows 10 or Windows 11 SDK are selected.
- Choose Modify to apply the changes and wait for setup to finish.
The workload supplies the compiler and libraries; the SDK supplies Windows headers and UCRT files. Selecting only one can leave a project incomplete.
2. Verify that the UCRT header exists
In File Explorer, open C:Program Files (x86)Windows Kits10Include. Open the SDK-version folder selected by the project and then the ucrt folder. Confirm that ctype.h is present. If the folder or file is absent, return to Visual Studio Installer and add the SDK component rather than copying a header from another installation.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
3. Select an installed SDK for the project
- Open the solution in Visual Studio.
- In Solution Explorer, right-click the project and choose Properties.
- Use the project’s Windows SDK or target-platform-version setting to select an SDK version that is actually installed.
- If the solution targets an SDK version that is no longer present, retarget it to an installed Windows 10 or Windows 11 SDK.
- Choose Apply and OK.
For multi-project solutions, check each project’s configuration. A solution can contain one project targeting an unavailable SDK even when another project is configured correctly.
4. Clean and rebuild
Use Build → Clean Solution, then Build → Rebuild Solution. A clean build forces Visual Studio to regenerate intermediate files with the selected SDK and include paths. Read the resulting compiler output, not only the red underline in the editor.
5. Repair Visual Studio if files are corrupted
If Visual Studio Installer says the components are installed but ctype.h or other SDK files are missing, open the instance’s menu and choose More → Repair. Microsoft’s repair operation can reacquire damaged installation files and reinstall existing assemblies. It also resets user settings, so export or note important custom settings first. After repair, reopen the solution, verify the SDK selection, and rebuild.
When only IntelliSense shows E1696
Visual Studio’s IntelliSense engine can report E1696 even when the compiler can build the project successfully. E#### messages are editor diagnostics; a real compiler failure normally appears as a C#### diagnostic in the build output.
- Run Build → Build Solution and inspect the Error List with the source set to Build + IntelliSense, then compare it with the build output.
- If the build succeeds and only the editor squiggle remains, verify the project’s selected SDK and configuration (for example, Debug versus Release).
- Close and reopen the solution after changing the SDK or workload so IntelliSense can reload its include paths.
- If necessary, allow Visual Studio to recreate its project browsing data by closing the IDE and reopening the solution after the component repair.
Do not install a launch-time redistributable merely to clear an IntelliSense underline. The runtime is used when an application runs; IntelliSense needs the SDK headers and a correct project configuration.
Best Value
Use the symptom to choose the remedy
| Symptom | Most likely cause | First action | How to verify |
|---|---|---|---|
Application dialog names MSVCP140.dll or VCRUNTIME140.dll. |
Missing, damaged, or mismatched Visual C++ runtime. | Install or repair the official redistributable matching the application’s architecture. | The application launches without the DLL dialog. |
| The application still fails after v14 installation. | It requires an older runtime such as 2013 or 2010, or a different architecture. | Check the vendor’s prerequisites and install the specified legacy package. | The vendor application starts; do not judge by the presence of an unrelated runtime entry. |
Visual Studio cannot open ctype.h and a build fails. |
Missing UCRT/Windows SDK or unavailable SDK target. | Add the C++ workload and SDK, select an installed SDK, then clean and rebuild. | The compiler completes without a missing-header C#### error. |
| Only an E#### IntelliSense message remains. | Editor include-path or cache mismatch. | Build the project, confirm the SDK configuration, and reload the solution. | A real build succeeds and no C#### diagnostic is emitted. |
| Installer lists components but files are absent. | Corrupted Visual Studio installation. | Use Visual Studio Installer More → Repair. | The expected SDK files return and the project rebuilds. |
Checks after applying a fix
- Launch the exact application that produced the original message, not just another program that happens to use C++.
- For Visual Studio, rebuild the same solution and configuration that failed before the change.
- Confirm that the selected architecture, runtime generation, and SDK version belong to the failing application or project.
- Keep older redistributables that another application still requires; removing them can break that application.
- If a vendor installer bundles its own prerequisite check, run it after the Microsoft package installation so it can validate all of its dependencies.
Common mistakes and recovery paths
Installing x64 for a 32-bit program
On 64-bit Windows, this is the most common architecture mistake. Install the x86 package for the 32-bit application. The Windows edition does not change the application’s architecture.
Assuming one runtime replaces every older release
v14 is the supported line for Visual Studio 2017–2026 applications, but software built with earlier toolsets can still require its matching 2013, 2010, or another legacy redistributable. Follow the application vendor’s stated prerequisite rather than uninstalling existing versions.
Changing include paths before installing the SDK
An include-path edit cannot create a missing ctype.h. Install the Windows SDK first, then select an installed SDK in project properties. Manual paths should be a last resort for a documented custom build, not a replacement for the Visual Studio workload.
Free tools Windows power users keep installed
One-click scans. No signup required.
Repairing Visual Studio without saving settings
Repair can reset user settings. Record custom keyboard mappings, extensions, and project-specific options before starting if they matter to your workflow.
Quick Recap
Optional shortcut
As an optional shortcut after trying the manual steps, Outbyte PC Repair can address more than 100 common Windows issues, including broken system elements and shared DLL problems, while offering settings adjustments, cleanup, vulnerability checks, and an app-crash log. It runs on Windows 11, 10, 8, and 7; its free trial lasts at least two days before a paid subscription. It complements antivirus software rather than replacing it, results vary, and no tool repairs every crash.
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.
