Error Loading Cefsharp.Core.Runtime.Dll

Ment to say latest ARC I tried to load and run was the 12.03 version. The 11.29 version worked perfectly fine.

Thanks - good details. This is a common symptom when the Chromium/CefSharp native runtime or one of its native dependencies is missing or blocked after an ARC update. CefSharp.Core.Runtime.dll is a native C++/CEF component and requires Windows CRT/VC++ runtime DLLs and the CEF native files to be present.

Here’s a focused troubleshooting checklist (try in order):

1. Confirm the DLL actually exists

• Open Explorer to your ARC install folder (default): C:\Program Files (x86)\Synthiam Inc\ARC by Synthiam\
• Search for CefSharp.Core.Runtime.dll (and CefSharp.*.dll)
• Or run PowerShell:

  Get-ChildItem -Path "C:\Program Files (x86)\Synthiam Inc\ARC by Synthiam" -Filter "CefSharp.Core.Runtime.dll" -Recurse
  

If the file is missing go to step 2. If it exists go to step 3.

2. Reinstall / Repair ARC 12.03

• The quickest fix if installer didn’t deploy CEF native files correctly: download ARC 12.03 and run the installer as Administrator (right-click Run as administrator) and choose Repair/Install.
• ARC Downloads: https://synthiam.com/Products/ARC
• After reinstall, try launching ARC and opening the Chromium skill.

3. Make sure Visual C++ runtimes are installed (very common cause)

• CefSharp native DLLs require the Microsoft VC++ Redistributable (Universal CRT). Install the latest supported Visual C++ Redistributables (both x86 and x64): Microsoft page: https://learn.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist
• Install the x86 and x64 packages, reboot, try ARC again.

4. Check for antivirus / quarantine

• Some AV products quarantine native DLLs after updates.
• Check Windows Defender quarantine or your AV logs and restore/allow CefSharp.Core.Runtime.dll and related Cef files. Add an exclusion on the ARC install folder and try again.

5. Find which dependency is actually failing (if the DLL is present but won’t load)

• Use the modern "Dependencies" tool to inspect CefSharp.Core.Runtime.dll for missing dependencies: Dependencies (GitHub): https://github.com/lucasg/Dependencies/releases
• Open CefSharp.Core.Runtime.dll with Dependencies and look for any red/missing modules (common misses: api-ms-win-crt-*.dll or MSVCP140.dll / VCRUNTIME140.dll).

6. Windows updates / UCRT

• If Dependencies shows missing api-ms-win-crt-runtime-l1-1-0.dll, you may need the Universal CRT which comes via Windows Update or via the Visual C++ redistributable above. Make sure Windows Update is current.

7. Permissions / Run as Admin

• Try running ARC as Administrator once to rule out permission errors.

8. Check ARC debug logs

• Since you have the Debug skill in your project, open it and copy the logged output (it may show more detail about missing modules). Paste the log or a screenshot if you want me to analyze it.

Additional notes

• You said 11.29 worked and 12.03 fails - ARC may have updated to a newer CefSharp/CEF build that requires a newer redistributable or different native files. Reinstalling ARC 12.03 or installing the latest VC++ redistributable almost always resolves this.
• Chromium skill manual: https://synthiam.com/Support/Skills/Display/Chromium?id=20391

If you want, I can:

• Walk you through using Dependencies to identify the missing module (tell me whether you want step-by-step).
• Interpret any output from the Debug skill or a Dependencies screenshot/log you paste here.

Quick checklist to try now:

1. Search for CefSharp.Core.Runtime.dll in the ARC folder.
2. Install Visual C++ Redistributable (x86 + x64) from Microsoft.
3. Reinstall/repair ARC 12.03 as Administrator.
4. Check AV quarantine and add exclusion for ARC folder.
5. If still failing, run Dependencies on the DLL and paste the missing-module names or a screenshot.

Which of those steps have you already tried? Do you see the CefSharp.Core.Runtime.dll file in your ARC folder?