Fix IIS recycle regressions by BrennanConroy · Pull Request #59998 · dotnet/aspnetcore

BrennanConroy · 2025-01-22T19:19:41Z

Fixes #58939 and both issues mentioned in #54531, both the empty path issue described in the initial post and the bad shutdown mentioned in #54531 (comment)

These were regressed by #52807

The two regressions were:

If any application in the same app pool (only OutOfProcess supports this) was modified we would end up triggering our shutdown logic even if it wasn't for our app, and additionally we shut down the whole w3wp process instead of just the specific application.
If disallowRotationOnConfigChange was true we would still shutdown the application on config changes.

The third fix wasn't a regression but was simple enough to fix and part of one of the issues linked above so included a fix for it. Our usage of _wcsicmp didn't properly check the path started with "MACHINE/WEBROOT", it would pass for "", or "MAC", "MACHINE/W", etc.

We have the test ConfigurationChangeCanBeIgnoredInProcess which should have caught one of the regressions, but since it was testing for the lack of app shutdown it doesn't have any way to know that nothing happened, fixed the test to have a bit of a delay so it has a better chance of failing in the future if we regress this.

We also have a multiple application test, but it was only running for IISExpress and it didn't have a restart scenario. Moved the test to the common tests so it's run by IIS as well and added a scenario where 1 of the applications restarts but the others don't.

BrennanConroy · 2025-01-22T19:24:03Z


        // This queue does not have websockets enabled currently, adding the module will break all tests using this fixture.
-        if (!HelixHelper.GetTargetHelixQueue().ToLowerInvariant().Contains("windows.amd64.server2022"))
+        if (!(HelixHelper.GetTargetHelixQueue() ?? "").ToLowerInvariant().Contains("windows.amd64.server2022"))


Fix local websocket tests.

BrennanConroy · 2025-01-22T19:24:46Z

-                <logFile logFormat="W3C" directory="%IIS_USER_HOME%\Logs" />
-                <traceFailedRequestsLogging directory="%IIS_USER_HOME%\TraceLogFiles" enabled="true" maxLogFileSizeKB="1024" />
+                <logFile logFormat="W3C" directory="%TEMP%\IISTests\Logs" />
+                <traceFailedRequestsLogging directory="%TEMP%\IISTests\TraceLogFiles" enabled="true" maxLogFileSizeKB="1024" />


Write logs to temp instead of user directory. If you know, you know.

Copilot

Copilot reviewed 5 out of 19 changed files in this pull request and generated no comments.

Files not reviewed (14)

src/Servers/IIS/AspNetCoreModuleV2/AspNetCore/applicationmanager.cpp: Language not supported
src/Servers/IIS/AspNetCoreModuleV2/AspNetCore/applicationmanager.h: Language not supported
src/Servers/IIS/AspNetCoreModuleV2/AspNetCore/globalmodule.cpp: Language not supported
src/Servers/IIS/IntegrationTesting.IIS/src/Http.SubApp.config: Language not supported
src/Servers/IIS/IntegrationTesting.IIS/src/Http.config: Language not supported
src/Servers/IIS/IIS/test/IISExpress.FunctionalTests/OutOfProcess/MultipleAppTests.cs: Evaluated as low risk
src/Servers/IIS/IntegrationTesting.IIS/src/IISDeploymentParameterExtensions.cs: Evaluated as low risk
src/Servers/IIS/IIS/test/Common.FunctionalTests/RequestResponseTests.cs: Evaluated as low risk
src/Servers/IIS/IIS/test/Common.LongTests/StartupTests.cs: Evaluated as low risk
src/Servers/IIS/IIS/test/Common.FunctionalTests/Infrastructure/EventLogHelpers.cs: Evaluated as low risk
src/Servers/IIS/IIS/test/Common.FunctionalTests/Infrastructure/IISTestSiteFixture.cs: Evaluated as low risk
src/Servers/IIS/IntegrationTesting.IIS/src/IISDeployerBase.cs: Evaluated as low risk
src/Servers/IIS/IntegrationTesting.IIS/src/IISExpressDeployer.cs: Evaluated as low risk
src/Servers/IIS/IIS/test/Common.FunctionalTests/MultiApplicationTests.cs: Evaluated as low risk

Comments suppressed due to low confidence (2)

src/Servers/IIS/IIS/test/Common.FunctionalTests/Infrastructure/Helpers.cs:259

Ensure that the change to select the last site element is covered by tests.

.Elements("site").Last();

src/Servers/IIS/IntegrationTesting.IIS/src/IISDeployer.cs:34

The variable _siteId is incremented without any checks or resets. This could potentially lead to an overflow if the application runs for a very long time and many sites are created. Consider adding a check to reset or handle the overflow scenario.

private int _siteId = 2;

captainsafia · 2025-01-29T20:43:41Z

    public static string OutOfProcessStarted(IISDeploymentResult deploymentResult)
    {
-        return $"Application '/LM/W3SVC/1/ROOT' started process '\\d+' successfully and process '\\d+' is listening on port '\\d+'.";
+        return $"Application '/LM/W3SVC/\\d+/ROOT' started process '\\d+' successfully and process '\\d+' is listening on port '\\d+'.";


Why are we loosening from strictly matching on 1 to any digit here? I see there are other updates related to multi-site handling in this PR. Does that address the regression or is it a new feature?

Multi-site handling was added to add test coverage for the regression. Technically we might be able to pass in the site id to these methods so it's not using regex.

captainsafia

Cursory LGTM!

hdez-es · 2025-03-11T07:57:39Z

Hello. I would like to know if there is an estimated date for this hotfix to be available so I can test it. I have 503 errors with MACHINE/WEBROOT and I believe this hotfix will resolve my issue.

If I run this command:
c:\windows\syswow64\inetsrv\appcmd.exe set config "mydomain.com" -section:compilation -tempDirectory:"%windir%\Microsoft.NET\custom-TemporaryASP.NETFiles\midomain.com" /commit:webroot

I get 503 errors on all websites on my server, and I have to recycle the application pool for all websites. This command started failing with .NET 9. Could this hotfix solve my problem?

bgrmwbys · 2025-05-23T13:54:15Z

@captainsafia why is this still open? It is ridiculous that such a critical bug is open for a few months now.

leepfrog-ger · 2026-01-22T16:20:57Z

Is there any ETA for getting that merged?

Copilot

Pull request overview

Copilot reviewed 20 out of 20 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (2)

src/Servers/IIS/IntegrationTesting.IIS/src/IISDeploymentParameterExtensions.cs:56

Inconsistent handling of access elements. In AddHttpsToServerConfig (lines 36-39), the code now uses a foreach loop to update all access elements, but in AddHttpsWithClientCertToServerConfig (lines 54-56), it still uses .Single() which will fail if there are multiple access elements in a multi-site configuration. This should also be changed to a foreach loop for consistency and to support multi-site scenarios.

                element.Descendants("access")
                    .Single()
                    .SetAttributeValue("sslFlags", "Ssl, SslNegotiateCert");

src/Servers/IIS/IIS/test/Common.LongTests/ShutdownTests.cs:520

The removal of deploymentParameters.HandlerSettings["disallowRotationOnConfigChange"] = "true"; changes the test behavior. The test name suggests it verifies that AppHost configuration changes are ignored, but without setting disallowRotationOnConfigChange, the test now verifies the default behavior where AppHost config changes should be ignored regardless. This makes the test less specific. Consider either updating the test name to reflect the actual behavior being tested or keeping the handler setting to test that the disallow setting works for AppHost config changes too.

        var deploymentParameters = Fixture.GetBaseDeploymentParameters(HostingModel.InProcess);

Copilot · 2026-02-06T04:29:00Z

+        // need some reasonable delay here to ensure the app has time to react to the file change notification
+        // In this case it should ignore it, but it's hard to test that the app doesn't do anything in reaction to the file change.
+        for (var i = 0; i < 2000; i++)
+        {
+            using var res = await deploymentResult.HttpClient.GetAsync("/ProcessId");
+            await Task.Delay(1);
+            Assert.Equal(HttpStatusCode.OK, res.StatusCode);
+            Assert.Equal(processBefore, await res.Content.ReadAsStringAsync());
+        }


The test improvement is good, but there's a potential timing issue. The loop makes 2000 requests with 1ms delay between each (total ~2 seconds). However, if the configuration change takes longer to process, the test might pass even if the app would eventually restart. Consider using a longer total duration or checking the logs to ensure the configuration change was actually processed and ignored.

BrennanConroy · 2026-03-12T19:01:15Z

@fhm20 @bgrmwbys @leepfrog-ger Can you try out the hosting bundle from 11.0-preview2 to see if the issues are resolved and there aren't any other problems? https://dotnet.microsoft.com/en-us/download/dotnet/11.0 using the following command line options to only install ANCM:
OPT_NO_RUNTIME=1 OPT_NO_SHAREDFX=1 OPT_NO_X86=1 see https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/hosting-bundle?view=aspnetcore-10.0#options

BrennanConroy added feature-iis Includes: IIS, ANCM area-networking Includes servers, yarp, json patch, bedrock, websockets, http client factory, and http abstractions labels Jan 22, 2025

BrennanConroy commented Jan 22, 2025

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BrennanConroy marked this pull request as ready for review January 22, 2025 22:23

BrennanConroy requested review from JamesNK, halter73 and mgravell as code owners January 22, 2025 22:23

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BrennanConroy added 10 commits February 1, 2026 22:29

wip

17f0628

wip

93beb8d

fixuo

58f1123

ignore config

127e60b

Fixups

558dd99

cleanup

4d14a65

using

a3289a6

using

6d7a557

just empty path check

8bd6136

fixup

3da5036

update test and rebase

4babaa5

BrennanConroy force-pushed the brecon/iisoutofprocessrecycle branch from f7fbf14 to 4babaa5 Compare February 2, 2026 21:00

Remove SkipOnHelix attribute from MultipleAppTests

106e919

build-analysis Bot mentioned this pull request Feb 3, 2026

Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. dotnet/dnceng#5922

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Comment thread src/Servers/IIS/AspNetCoreModuleV2/AspNetCore/applicationmanager.h Outdated

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Comment thread src/Servers/IIS/IIS/test/IIS.Tests/Utilities/TestServer.cs Outdated

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BrennanConroy merged commit 6e66a7e into main Feb 10, 2026
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BrennanConroy deleted the brecon/iisoutofprocessrecycle branch February 10, 2026 04:32

dotnet-policy-service Bot added this to the 11.0-preview2 milestone Feb 10, 2026

This was referenced Feb 10, 2026

IIS dotnet process shutdown with .NET 10 runtime installation #64808

Closed

IIS AspNetCoreModuleV2: random/endless recycles #54531

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dotnet-maestro Bot mentioned this pull request Feb 11, 2026

[main] Source code updates from dotnet/aspnetcore dotnet/dotnet#4784

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