Windows Application Log · Event 1026
Event 1026: A .NET program threw an exception nobody caught
A program written on the .NET framework hit an error its own code did not handle, so the runtime shut it down. Unlike most crash events, this one carries a stack trace — the list of methods that were running — which usually names the responsible component outright.
Also written as NET Runtime 1026.NET Runtime error 1026clr20r3
- How oftenFires regularly
- Vendor calls itError
- LogApplication
- Source.NET Runtime
The fields that decide it
Everything else in the log line is context.
- Application
- The executable that died, and the framework version it was built against. A v2.0.50727 line means the old .NET Framework 2/3.5 runtime, which behaves differently from v4.
- Description
- Always 'The process was terminated due to an unhandled exception.' Nothing useful lives here.
- Exception Info
- The exception type, which is the single most informative field in the event.
-
System.NullReferenceExceptionA plain bug in the application's code. -
System.IO.FileNotFoundExceptionA missing file or a missing dependency, often a failed or partial install. -
System.UnauthorizedAccessExceptionA permissions problem — frequently the service account rather than the code. -
System.Net.WebException or System.Net.Http.HttpRequestExceptionIt could not reach something over the network. Check the endpoint before the program. -
System.Configuration.ConfigurationErrorsExceptionA broken or missing config file, common straight after a deployment. -
System.OutOfMemoryExceptionThe process exhausted its address space, which on a 32-bit process happens well below the machine's free memory. - Stack
- The call stack at the moment of failure, innermost frame first. The first non-Microsoft namespace in the list is normally the code at fault.
- Framework Version
- Which CLR was hosting the process. Matters because .NET Framework and .NET (Core) write different events — a modern .NET application usually logs Event 1000 from '.NET Runtime' rather than this.
Common questions
What does exception code 0xe0434352 mean?
It is the .NET runtime's way of surfacing a managed exception to Windows, so it appears in Application Error 1000 for essentially every .NET crash. It tells you the language, not the problem. The useful detail is in the paired Event 1026, which names the actual exception type and the stack.
How do I read the stack trace in Event 1026?
Read it top down: the first line is where the failure happened, and each line below is the method that called it. Skip past the frames in System.* and Microsoft.* namespaces — the first frame in the application's own namespace is where its code lost control, and that is what needs fixing or reporting.
Why do I get Event 1026 but no crash dialog?
Windows Error Reporting can be configured to close the process silently, and services never show a dialog at all. The event is written either way, which is why the Application log often holds the only evidence that something restarted overnight.
Does Event 1026 mean .NET is broken on my machine?
Almost never. It means one program written in .NET hit a bug. If several unrelated .NET programs start failing at once with FileNotFoundException or TypeLoadException, that is a different picture and points at a botched framework update — but a single application failing repeatedly is that application's problem.
Read next
- Read alongside Event 1000: An application crashed The Application Error crash logged alongside this one, with exception code 0xe0434352 — the CLR's marker for a managed exception.
- Usually comes after Event 1001: Windows Error Reporting filed a crash report The Windows Error Reporting record, which shows whether a dump was kept.
- The equivalent of Event 33: A program cannot find a runtime library it needs A SideBySide failure, the other common way a program dies before it really starts.
- Read alongside Event 7031: A service terminated unexpectedly When the crashing .NET program is a Windows service, this is the service-failure event that follows.
Mentioned by
Vendor documentation
Last reviewed 6 September 2026