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Why does ST-Link Server say SWO is not available?

Associate II

I configured IAR EWARM for dual core debugging of an STM32H7 processor following instructions from one of ST's application notes (AN5286).

When I do, I get the following warning repeated endlessly in the log window:

"Tue May 26, 2020 10:13:04: SWO not available when using ST-Link server"

This could be an IAR / EWARM issue, but I'm guessing that the log window is just piping through whatever messages ST-Link Server sends it.

Imen Ezzine
ST Employee

Hi R.Keelan ,

Did you try to update the firmware for ST-Link?

Let me know what version of Ewarm you use to see if I can help? Does it support the shared mode feature?


Associate II


I reported the issue to IAR as well, and they seem to think the warning is coming from their side, that some component of IAR is trying to use SWO even though it shouldn't be.

But, for your reference, the ST-Link version is V3J3M2, and the IAR version 8.40.2.


An IAR Technical Support Engineer indicated to my colleague R.Keelan, that starting in IAR EWARM version 8.50.6, the warning "SWO not available when using ST-Link server" will show up once only. We'll probably upgrade to that version of IAR sometime soon.