How to troubleshoot API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL errors

A API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL-specific sequence based on Universal CRT API Set and its supported delivery through Windows Universal CRT.

1

Identify the Universal CRT runtime API-set contract

Record the affected program, exact API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL message, Windows version, and whether the app is 32-bit or 64-bit.

2

Restore the complete Universal CRT deployment

Open Settings > Windows Update, select Check for updates, install all applicable updates, and restart. If the Windows component remains damaged, open Command Prompt as administrator, run DISM RestoreHealth, wait for completion, and then run SFC.

3

Verify the runtime forwarder set as one package

Restart Windows after the supported repair, launch the same affected program, and repeat the action that produced the original message. If API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL still fails, record the new exact error and stop before making unrelated system changes.

Safety warning: Do not copy or register API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL in isolation. API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL belongs to the Universal CRT API Set family and this report does not identify it as a self-registering COM server. Repair it through Windows Update, DISM, and SFC instead of attempting manual registration.

Windows Repair Intelligence™ DLL Report

API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL

Universal CRT Runtime API-Set Forwarder

Home / DLL Library / Universal CRT API Set / API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL

An API-set contract used by applications to reach Universal C Runtime functionality on supported Windows systems.

PublisherMicrosoftArchitecturesx86 / x64Source classWindows componentReviewedAugust 15, 2026

What is API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL?

API-MS-WIN-CRT-RUNTIME-L1-1-0.dll is an API-set forwarder in the Universal CRT deployment. It connects application imports to the operating system's UCRT implementation.

Common Error Messages

  • "api-ms-win-crt-runtime-l1-1-0.dll was not found"
  • "The code execution cannot proceed because api-ms-win-crt-runtime-l1-1-0.dll is missing"
  • "api-ms-win-crt-runtime-l1-1-0.dll is either not designed to run on Windows or it contains an error"

Common Causes

  • The Universal CRT update is missing on an older supported system
  • Windows servicing is incomplete
  • An application-local UCRT deployment omitted required forwarders
AI

Smart diagnostic checkpoint

AI-assisted · grounded in this report's reviewed evidence
Package ownerWindows Universal CRT

Serviced through Windows—not a loose DLL download.

Best first routeRestore the complete Universal CRT deployment

Match the affected program and x86 / x64 architecture before repairing.

System repair?Applicable after evidence checks

Use DISM, then SFC, only after updating Windows and checking the affected component.

Stop and reassessIf the exact message changes

Capture the new wording and affected program. Do not continue repeating unrelated repairs.

Fix the program that reports API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL

This decision path is specific to Universal CRT Runtime API-Set Forwarder. An API-set contract used by applications to reach Universal C Runtime functionality on supported Windows systems.

1

Preserve evidence from the API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL dialog

Note the affected program, the action that triggered the failure, and what changed immediately beforehand. Save open work and close that program normally; use Task Manager only if it is frozen or the supported repair tool says it is still running.

Record the exact message “api-ms-win-crt-runtime-l1-1-0.dll was not found” before closing it.
2

Decide whether the failure is app-local or Windows-wide

If one program alone reports API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL, repair that program first. If unrelated programs or Windows features fail too, check Windows Update history and service the complete Windows Universal CRT rather than copying one API-set or runtime file.

Protected location to verify after servicing: C:\Windows\System32\api-ms-win-crt-runtime-l1-1-0.dll.
3

Restore the complete Universal CRT deployment

Install all applicable Windows updates. Then repair the affected application's official prerequisites. Use Repair or Change only when Windows or the official installer actually offers that option.

Use Universal CRT deployment as the evidence route; do not download API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL separately.
4

Verify the runtime forwarder set as one package

Run DISM followed by SFC. Launch the same program and repeat the original action. If the wording changes, capture the new error and reassess instead of repeating unrelated repairs.

Validation target: The Universal CRT update is missing on an older supported system.

Page-specific safety boundary: API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL is serviced as Windows Universal CRT. Resetting an application may erase its data but cannot replace an unsupported Windows API or hardware feature.

Verified file intelligence

Official-source grounded

Versions, hashes, and signatures can vary by supported package release. This report does not invent a universal "latest file" value. Confirm package selection against Universal CRT deployment (Microsoft Learn), Use the System File Checker tool (Microsoft Learn).

Verified API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL file versions

12 observed builds

Distinct locally observed specimens are deduplicated by version, architecture, and SHA-256. A signature result identifies the inspected file; it is not a recommendation to copy a loose DLL into Windows.

VersionArchitectureFile sizeLanguageSignature
10.0.10240.16384 (th1.150709-1700)x6433.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-2562d38ad5d17550138586de4dca3c2bc00a334d8a825f5e3e707298defbc985a04
10.0.10240.16384 (th1.150709-1700)x6433.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-2563676a5ccbce9155b0c566395d81882e83b07a79482e5ed196ef27e09a301a7f4
10.0.10240.16384 (th1.150709-1700)x6433.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-25648b74caa668c18ad2e3a81dce9ce069ad6186774b9d7e1bea67a88d45a87b833
10.0.10240.16384 (th1.150709-1700)x6433.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-256a72fb2369967e76bc796e8a2e876d3d23e86215b3a216bec70c3bb9663a9ae51
10.0.10240.16384 (th1.150709-1700)x6433.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-256c2f994ffe3bd7d382e737e11a9e28aff6ca060cf282f83d26ce4894440f86a0b
10.0.10240.16384 (th1.150709-1700)x8633.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-2562328932c57b7175e2acb7b917c5532477b51e7878920efadf2d5ff76d172aff7
10.0.10240.16384 (th1.150709-1700)x8633.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-25625a2eee49d64f7cfc98b23fa10459f5d01dbe26b8bae9cbfd251324b59cf9f67
10.0.10240.16384 (th1.150709-1700)x8633.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-2564882af30a82398699bacf66b2bceb3aa153247a5c5a165566e1ca5919a535c4e
10.0.10240.16384 (th1.150709-1700)x8633.1 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-256769f15934c63a4554675815fa6370147edc761621d16fb94c01845658366fcf5
10.0.22621.2428 (WinBuild.160101.0800)x6426.4 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-2561701054bf02f88c7278686e134e8a960c54da3e8dac7dd6814373a244ff678d8
10.0.26100.1 (WinBuild.160101.0800)x6425.4 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-2565d8e35ef54c87d44c9c741af07146e8146749a6f5b947fd3b71a392c80049f89
10.0.26100.1 (WinBuild.160101.0800)x8617.3 KBEnglish (United States)Valid
PublisherMicrosoft CorporationDescription / observed sourceApiSet Stub DLL · Installed applicationSHA-2563053974118aae49bf25fc0ec15b9816debaf9bd4cdb3097639039b50451001c9

Evidence method: file metadata read from the observed specimen, SHA-256 calculated by WinLab, and digital-signature status checked through Windows Authenticode. Observed 2026-08-31.

Frequently Asked Questions

AI-assisted / evidence reviewed

How we use AI: AI helps draft clear answers, but every published technical claim must be tied to an approved source, pass safety checks, and receive editorial review. It may not invent versions, hashes, signatures, download links, or success rates.

What is API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL?

API-MS-WIN-CRT-RUNTIME-L1-1-0.dll is an API-set forwarder in the Universal CRT deployment. It connects application imports to the operating system's UCRT implementation.

Why is API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL missing or failing?

The Universal CRT update is missing on an older supported system; Windows servicing is incomplete; An application-local UCRT deployment omitted required forwarders. For API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL, confirm the owning Windows Universal CRT installation before concluding that Windows itself is damaged.

What is the safest way to repair API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL?

Install all applicable Windows updates; Repair the affected application's official prerequisites; Run DISM followed by SFC. It is a contract component, so manually copying one forwarder without the rest of the required UCRT set is unsafe and incomplete.

Can I safely download API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL from a DLL website?

Do not restore API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL as an isolated download. Its supported owner is Windows Universal CRT; use Windows servicing and the System File Checker so architecture, companion files, and servicing metadata remain consistent. It is a contract component, so manually copying one forwarder without the rest of the required UCRT set is unsafe and incomplete.

Should I run regsvr32 for API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL?

API-MS-WIN-CRT-RUNTIME-L1-1-0.DLL belongs to the Universal CRT API Set family and this report does not identify it as a self-registering COM server. Repair it through Windows Update, DISM, and SFC instead of attempting manual registration.