Crash with Task Watchdog when performing OTA update

[dirkvranckaert]

IDE / Tooling

Arduino (IDE/CLI)

What happened?

Am on the latest version of the repo and trying to install an OTA update. The result of the AyncTCP backend call gives me back the OTA url and then I start perfoming the OTA update.

However in a lot of scenarios I see this error coming by followed by a stacktrace and a reboot off course:

E (23445) task_wdt: Task watchdog got triggered. The following tasks/users did not reset the watchdog in time:
E (23445) task_wdt:  - async_tcp (CPU 0)
E (23445) task_wdt: Tasks currently running:
E (23445) task_wdt: CPU 0: async_tcp
E (23445) task_wdt: Aborting.
E (23445) task_wdt: Print CPU 0 (current core) registers

Lots of these devices are remote so I cannot debug, but some do get through (I guess with a lot of luck). But on my testing device here I see this issue all the time...

Stack Trace

10:43:37.717 -> ------------------------------------------
10:43:37.717 -> Software Info:
10:43:37.717 -> ------------------------------------------
10:43:37.717 -> Compile Date/Time : Feb 4 2026 10:40:55
10:43:37.717 -> Compile Host OS : macosx
10:43:37.717 -> ESP-IDF Version : v5.5.1-931-g9bb7aa84fe
10:43:37.717 -> Arduino Version : 3.3.5
10:43:37.717 -> ------------------------------------------
10:43:37.717 -> Board Info:
10:43:37.717 -> ------------------------------------------
10:43:37.749 -> Arduino Board : ESP32C6_DEV
10:43:37.749 -> Arduino Variant : esp32c6
10:43:37.749 -> Arduino FQBN : esp32:esp32:esp32c6:UploadSpeed=460800,CDCOnBoot=default,CPUFreq=160,FlashFreq=40,FlashMode=qio,FlashSize=8M,PartitionScheme=default_8MB,DebugLevel=debug,EraseFlash=none,JTAGAdapter=default,ZigbeeMode=default
10:43:37.749 -> ============ Before Setup End ============
10:43:38.067 -> [WiFi-event] (101) :WiFi interface ready
10:43:38.165 -> [WiFi-event] (110) :WiFi client started
10:43:38.165 -> Setting up RTC...
10:43:38.165 -> [ 634][I][esp32-hal-i2c-ng.c:112] i2cInit(): Initializing I2C Master: num=0 sda=6 scl=7 freq=100000
10:43:38.165 -> [ 648][W][Wire.cpp:300] begin(): Bus already started in Master Mode.

Minimal Reproductible Example (MRE)

Hard to post an MRE here since it requires different versions and OTA upgrade mechanism...

I confirm that:

• I have read the documentation.
• I have searched for similar discussions.
• I have searched for similar issues.
• I have looked at the examples.
• I have upgraded to the lasted version of AsyncTCP.

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⚠️ Possible Duplicate Issue

• Maybe timing problem #92

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[mathieucarbou]

Hi @dirkvranckaert ,
Moving that to a support ticket (you can even search you will find some answers already on that).
This errors proves that you have some code issues, blocking the async_tcp task and as such, the watchdog triggers to reboot the esp.
this is not a bug in the library but more a protection against bad programming on user-side.
if you really need to disable the watchdog, at the risk of of dead-locking your esp, you can with a macro flag (see the headers / cpp file).
you need to make sure that every time your code is called from the async_tcp task, it must be as fast as possible, mut not call blocking I/O, must not block, delay or any thing like that.