Random SIGABRT in libmonodroid on .NET 10 Release (arm64): "Cannot transition thread … with DONE_BLOCKING" on .NET TP Worker

The abort comes from xamarin::android::Helpers::abort_application in libmonodroid, triggered by a thread-state transition conflict ('Cannot transition thread … with DONE_BLOCKING' / 'ASYNC_SUSPEND_REQUESTED') on a .NET TP Worker thread during HTTPS downloads. Start by reading the runtime's thread state machine and GC suspend handling around that abort path, then compare against the possibly related #10659 and #10910. The crash is not reproducible on demand, so the first concrete step is asking the reporter for a MONO_LOG_LEVEL/GC diagnostic run rather than attempting a patch; 'done' would be a reproduced state transition plus a fix.

Android framework version

net10.0-android

Affected platform version

.NET 10

Description

Android framework version

net10.0-android

Affected platform version

Android 14 (HONOR CLK-LX1EEA, arm64-v8a, build HNCLK-Q:14/HONORCLK-L31/8.0.0.424C431E9R2P3)

Description

After upgrading an app from an older stack to .NET 10 (MAUI 10.0.100, F#, Fabulous 10.0.3), the Release build aborts at random while running long network downloads. Windows (net10.0-windows) is unaffected, and the previous version of the app (older .NET/MAUI/Fabulous) was stable on the same phone.

There is no managed exception or managed stack trace. The runtime calls abort() itself from xamarin::android::Helpers::abort_application, always on a .NET TP Worker thread, with one of these messages:

Abort message: 'Cannot transition thread 0x… from RUNNING with DONE_BLOCKING'
Abort message: 'Cannot transition thread 0x… from ASYNC_SUSPEND_REQUESTED with DONE_BLOCKING'

Backtrace (identical in all cases):

#00 libc.so (abort+164)
#01 libmonodroid.so (xamarin::android::Helpers::abort_application(_LogCategories, char const*, bool, std::__ndk1::source_location)+584)

Five crashes were observed, uptimes 11/152/358/543/582 s. The last but one one (543 s) is the ASYNC_SUSPEND_REQUESTED variant and happened on a clean build with AndroidEnableMarshalMethods=false, so marshal methods are not the cause. The crash is not reproducible on demand: some runs complete the download, others abort. Memory is not the cause (RSS ≈ 300–350 MB at the time of the abort). Still crashing with all runtime options disabled

dumpsys activity exit-info reports reason=5 (APP CRASH(NATIVE)), description=crash.

The ASYNC_SUSPEND_REQUESTED state suggests a race between a GC suspend and a thread returning from a blocking call, but I cannot confirm this.

What the app does

• Downloads many files over HTTPS with HttpClient (via FsHttp) on thread-pool threads, using F# async and MailboxProcessor.
• Runs a foreground service of type dataSync while downloading.
• Registers a ConnectivityManager callback and polls network state.
• Reports progress to a Fabulous/MAUI UI from background threads.

Settings tested

Configuration	Result
Release, defaults (marshal methods on)	crashes (3×)
Release, AndroidEnableMarshalMethods=false, clean build	crashes (1×, ASYNC_SUSPEND_REQUESTED)
[+ AndroidEnableSGenConcurrent=false, AndroidEnableProfiledAot=false, RunAOTCompilation=false, PublishTrimmed=false, RuntimeIdentifier=android-arm64]	[fill in: N runs, result]
Debug build	[fill in, if tested]

Steps to reproduce

Not reliably reproducible. Run the app on the device above and start a long-running download of many files. It aborts at an unpredictable moment, between 10 s and 10 minutes after launch. I can provide a build or a project on request, and I can run any diagnostic build or MONO_LOG setting that would help.

Environment

dotnet --info:

PS C:\Program Files (x86)\Android\android-sdk\platform-tools> dotnet --info
.NET SDK:
 Version:           10.0.401
 Commit:            e34a38d2ae
 Workload version:  10.0.401.1
 MSBuild version:   18.9.11+e34a38d2a

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19045
 OS Platform: Windows
 RID:         win-x64
 Base Path:   C:\Program Files\dotnet\sdk\10.0.401\

.NET workloads installed:
 [android]
   Installation Source: SDK 10.0.400, VS 18.10.12224.181
   Manifest Version:    36.1.69/10.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.android\36.1.69\WorkloadManifest.json
   Install Type:              Msi

 [ios]
   Installation Source: SDK 10.0.400, VS 18.10.12224.181
   Manifest Version:    27.0.10722/10.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.ios\27.0.10722\WorkloadManifest.json
   Install Type:              Msi

 [maccatalyst]
   Installation Source: SDK 10.0.400, VS 18.10.12224.181
   Manifest Version:    27.0.10722/10.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.maccatalyst\27.0.10722\WorkloadManifest.json
   Install Type:              Msi

 [maui]
   Installation Source: SDK 10.0.400
   Manifest Version:    10.0.110/10.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.maui\10.0.110\WorkloadManifest.json
   Install Type:              Msi

 [maui-windows]
   Installation Source: SDK 10.0.400, VS 18.10.12224.181
   Manifest Version:    10.0.110/10.0.100
   Manifest Path:       C:\Program Files\dotnet\sdk-manifests\10.0.100\microsoft.net.sdk.maui\10.0.110\WorkloadManifest.json
   Install Type:              Msi

Configured to use workload sets when installing new manifests.

Host:
  Version:      10.0.12
  Architecture: x64
  Commit:       95017c711e

.NET SDKs installed:
  8.0.425 [C:\Program Files\dotnet\sdk]
  9.0.302 [C:\Program Files\dotnet\sdk]
  9.0.306 [C:\Program Files\dotnet\sdk]
  9.0.309 [C:\Program Files\dotnet\sdk]
  9.0.318 [C:\Program Files\dotnet\sdk]
  10.0.401 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 3.1.32 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.4 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.23 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 8.0.31 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.10 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 9.0.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 10.0.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 3.1.32 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.23 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.27 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 8.0.31 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.10 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 9.0.20 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 10.0.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 8.0.4 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.21 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.23 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 8.0.31 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.7 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.10 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.12 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 9.0.20 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 10.0.12 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

dotnet workload list:

PS C:\Program Files (x86)\Android\android-sdk\platform-tools> dotnet workload list

Workload version: 10.0.401.1

Installed Workload Id      Manifest Version         Installation Source
------------------------------------------------------------------------------------
android                    36.1.69/10.0.100         SDK 10.0.400, VS 18.10.12224.181
ios                        27.0.10722/10.0.100      SDK 10.0.400, VS 18.10.12224.181
maccatalyst                27.0.10722/10.0.100      SDK 10.0.400, VS 18.10.12224.181
maui                       10.0.110/10.0.100        SDK 10.0.400
maui-windows               10.0.110/10.0.100        SDK 10.0.400, VS 18.10.12224.181

Use `dotnet workload search` to find additional workloads to install.

Relevant packages: Microsoft.Maui.Controls 10.0.100, FSharp.Core 10.0.100, Fabulous 10.0.3, Fabulous.MauiControls 10.0.3, FsHttp 15.0.3, Microsoft.Data.SqlClient 7.0.2.
Target: net10.0-android, SupportedOSPlatformVersion 30, AndroidTargetSdkVersion 36, RID android-arm64, Release, APK.

Related reports

Possibly related to #10659 (SIGABRT in Mono assertions on .NET 10 Release, arm64) and to the marshal-methods crashes in #10910, although the latter setting did not fix this case.

Logs

Full logcat -b crash output attached ([crash.txt]) together with the exit-info dump.

--------- beginning of crash
10-04 13:30:42.667 8572 8953 F libc : Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 8953 (.NET TP Worker), pid 8572 (eDownloaderMAUI)
10-04 13:30:43.970 21212 21212 F DEBUG : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
10-04 13:30:43.970 21212 21212 F DEBUG : Build fingerprint: 'HONOR/CLK-LX1EEA/HNCLK-Q:14/HONORCLK-L31/8.0.0.424C431E9R2P3:user/release-keys'
10-04 13:30:43.970 21212 21212 F DEBUG : Revision: '0'
10-04 13:30:43.970 21212 21212 F DEBUG : ABI: 'arm64'
10-04 13:30:43.970 21212 21212 F DEBUG : Timestamp: 2026-10-04 13:30:42.835120156+0200
10-04 13:30:43.970 21212 21212 F DEBUG : Process uptime: 358s
10-04 13:30:43.970 21212 21212 F DEBUG : Cmdline: com.companyname.OdisTimetableDownloaderMAUI
10-04 13:30:43.970 21212 21212 F DEBUG : pid: 8572, tid: 8953, name: .NET TP Worker >>> com.companyname.OdisTimetableDownloaderMAUI <<<
10-04 13:30:43.970 21212 21212 F DEBUG : uid: 10414
10-04 13:30:43.970 21212 21212 F DEBUG : tagged_addr_ctrl: 0000000000000001 (PR_TAGGED_ADDR_ENABLE)
10-04 13:30:43.970 21212 21212 F DEBUG : signal 6 (SIGABRT), code -1 (SI_QUEUE), fault addr --------
10-04 13:30:43.970 21212 21212 F DEBUG : Abort message: 'Cannot transition thread 0x7532bfbc30 from RUNNING with DONE_BLOCKING'
10-04 13:30:43.971 21212 21212 F DEBUG : x0 0000000000000000 x1 00000000000022f9 x2 0000000000000006 x3 0000007532bf9af0
10-04 13:30:43.971 21212 21212 F DEBUG : x4 ff4854404c716463 x5 ff4854404c716463 x6 ff4854404c716463 x7 7f7f7f7f7f7f7f7f
10-04 13:30:43.971 21212 21212 F DEBUG : x8 00000000000000f0 x9 000000793b6b5a98 x10 0000000000000001 x11 000000793b6fd540
10-04 13:30:43.971 21212 21212 F DEBUG : x12 00000000000081aa x13 0000000000000004 x14 ffffffffffffffff x15 0000000000000000
10-04 13:30:43.971 21212 21212 F DEBUG : x16 000000793b761f38 x17 000000793b73f370 x18 0000007531d10000 x19 000000000000217c
10-04 13:30:43.971 21212 21212 F DEBUG : x20 00000000000022f9 x21 00000000ffffffff x22 b4000076db2cd540 x23 000000766d91d2a8
10-04 13:30:43.971 21212 21212 F DEBUG : x24 0000007532bf9c20 x25 0000007532bf9bb8 x26 0000007532bf9bd0 x27 0000000000204000
10-04 13:30:43.971 21212 21212 F DEBUG : x28 0000007532bfa560 x29 0000007532bf9b70
10-04 13:30:43.971 21212 21212 F DEBUG : lr 000000793b6eed94 sp 0000007532bf9ad0 pc 000000793b6eedc0 pst 0000000000000000
10-04 13:30:43.971 21212 21212 F DEBUG : 2 total frames
10-04 13:30:43.971 21212 21212 F DEBUG : backtrace:
10-04 13:30:43.971 21212 21212 F DEBUG : #00 pc 000000000005bdc0 /apex/com.android.runtime/lib64/bionic/libc.so (abort+164) (BuildId: d638ba9bdf4cea2cddd9bd06ae04407f)
10-04 13:30:43.971 21212 21212 F DEBUG : #01 pc 00000000000a438c /data/app/~~vLDur6GYacC1R4fWA3xIXA==/com.companyname.OdisTimetableDownloaderMAUI-YzUo479gy1jCCHv6DkxnZw==/lib/arm64/libmonodroid.so (xamarin::android::Helpers::abort_application(_LogCategories, char const*, bool, std::__ndk1::source_location)+584) (BuildId: ae7ad8820dd75996ecdee692e377f8586298ceb0)

ACTIVITY MANAGER PROCESS EXIT INFO (dumpsys activity exit-info)
Last Timestamp of Persistence Into Persistent Storage: 2026-10-04 13:23:30.635
package: com.companyname.OdisTimetableDownloaderMAUI
Historical Process Exit for uid=10414
ApplicationExitInfo #0:
timestamp=2026-10-04 13:30:44.023 pid=8572 realUid=10414 packageUid=10414 definingUid=10414 user=0
process=com.companyname.OdisTimetableDownloaderMAUI reason=5 (APP CRASH(NATIVE)) subreason=0 (UNKNOWN) status=6
importance=100 pss=227MB rss=325MB description=crash state=empty trace=null

Steps to Reproduce

The crash is intermittent and I could not reduce it to a minimal project yet, but it reproduces within minutes on my device with the full app:

1. Build the app (net10.0-android, Release, RuntimeIdentifier android-arm64, signed APK) and install it on an HONOR CLK-LX1EEA running Android 14 (arm64).
2. Launch the app and start a long-running download (many HTTPS file downloads on thread-pool threads, using HttpClient with F# async; a foreground service of type dataSync is running during the download; progress is reported to the UI while downloading).
3. Wait. In most runs the process aborts at an unpredictable moment between 11 seconds and about 10 minutes after launch. Some runs finish the whole download without a crash.
4. After the crash, adb logcat -b crash -d shows SIGABRT on a ".NET TP Worker" thread with "Cannot transition thread … from RUNNING (or ASYNC_SUSPEND_REQUESTED) with DONE_BLOCKING", raised from xamarin::android::Helpers::abort_application.

Observed so far: 5 crashes at process uptimes of 11 s, 152 s, 358 s, 543 s and 582 s.

Still crashes with all of these set (clean build, bin/obj deleted):

• AndroidEnableMarshalMethods=false
• AndroidEnableSGenConcurrent=false
• AndroidEnableProfiledAot=false, RunAOTCompilation=false
• PublishTrimmed=false
• single RID android-arm64

Not affected: the same app on Windows (net10.0-windows), and the previous version of the app built with an older .NET/MAUI/Fabulous stack on the same phone.

I have no minimal reproduction project yet. I'm happy to test any diagnostic build or environment setting (for example MONO_LOG_LEVEL / debug.mono.log), and to attach a full adb logcat -v threadtime from a crash.

Did you find any workaround?

No response

Relevant log output

##Updating the bug report

The issue is now much more concrete:

Trigger:
System.Net.NetworkInformation.Ping.Send called from parallel thread-pool work on Android (.NET 10, Release, arm64), while other work runs. With the ping removed and everything else the same, no crashes in N runs. With the ping restored, crashes returned.
Reproduction: this makes a small test app realistic: a loop that runs Async.Parallel over two Ping.Send calls on thread-pool threads, plus some allocation or download activity in the background. If that crashes on your phone too, you have a real minimal repro, and a bug with a repro is far more likely to get attention than "random crash in a big app".

The entire source code of the app is in a private repository, but it can be made available to the maintainers of this repository upon request. See the Fabulous repository (https://github.com/fabulous-dev) for a contact email address.