In VSC Task Window always popping up: "Error: No handler found"

I’m using Platformio on Visual Studio Code on an Windows 10 machine.
It’s running fine, but in my project i always get an annoying “Error: no handler found” error when i start tasks like build or upload.

I have no clue what’s causing this. Any hints how to solve this?


Can you upload a full log when executing pio run -v to here or

I’m sorry, i can’t, because there are too many private entries in the log.
What does “no handler” mean? Where to look for the cause?

Oh actually I realized that you say that it’s a VSCode popup and not some text printed in the compilation or the upload. As thus these logs don’t help. Well then, I have no idea where such an error could be thrown, but maybe @ivankravets does? Can you provide a screenshot of that error?

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I think this error occurs after a task job is started, like build or upload. Maybe something with the (python?) scripts behind the task buttons?

Could be this error from visual studio code:

I’ve had that issue a few months, at least. No ill effects on operation…so I just ignore it.

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Can’t ignore it, since it everytime forces me to press button to get rid of the popup

That’s popping up for me also, with ESP8266 and AVR projects on linux and more than one machine now… doesn’t seem to be causing any issues, but it is a bit disconcerting that it keeps popping up…

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i don’t get a popup. it just appears in my compile window.

Then you probably did not yet the lastet VSC Upgrade, with this a Popup appears each time the error occurs in Task Window. And i did not yet find the setting to suppress this.

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latest-greatest here.

Same here… 1.31 IIRC, and a popup comes up at the bottom right every time that needs to clicked to get rid of it… prior to that it was just a message in the log that went away when it switched to the task terminal.

Can confirm I am also getting this and it’s been bugging me. Doesn’t prevent build from failing. Just every time I build.

Not a confidential project so can provide logs if necessary…

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I can also confirm seeing this on the latest VSCode. I’ve seen the “no handler found” error for a couple months but it was non-intrusive, but with the latest update to VSCode it now has the popup which doesn’t get automatically dismissed. This seems to be a bug in the PIO plugin but I haven’t dug into where/what is missing myself.

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This is a problem for me, as well.

My setup:

PlatformIO Version: 1.6.0 (2018-12-12)
VSCode Version: 1.31.1 (1.31.1)
macOS Mojave 10.14.2

I have been seeing the “Error: No handler found” errors in the OUTPUT window/tab for quite some time; however the popup window is relatively recent.

Is there any clarity whether this is a native VSCode problem or PIO?

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Same problem here, the pop up is annoying


I’ve had that same issue on two debian linux boxes now running VSCode 1.31.1 and PIO Core 3.6.4, and I think it’s related to program AVR / Arduino environments, as my AVR (328p uno and 8mhz bare) projects are giving that error, but my ESP8266 (Arduino also) ones are fine - no errors from them?

Without having tested that it would make sense as my machine at home (AVR/Arduino platform and espressif platform installed) throws those errors as I build for the ESP8266 with Arduino and my machine at work (only espressif) doesn’t (building ESP32 with ESP-IDF)… Both are Win10, VSCode 1.31.1 and PIO Core 3.6.4.