BLE connection issue (error 8) with nRF54H20 + Zephyr

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Simonr — Wed, 01 Apr 2026 07:05:00 GMT

I was asked to take a look at this ticket, and everything here points to the issue here being with either the HFXO or LFXO crystal on your custom boards either being mounted poorly or loaded incorrectly.

These error messages in the past and the fact that some boards work correctly points very much to this being the case.

Can you:

Upload the specifications for the crystals you're using in your design so we can verify they are suitable for your design. (Both 32.768kHz and 32MHz)
Share details on how they are loaded (I assume you're using internal capacitors and not external ones)?
Verify with a scope or similar that the external crystals are outputting the expected frequencies and that they are mounted physically correct on the boards. A common mistake here is to mount either crystal 90 degrees the wrong way if it has 4 mounting pads, and that would result in these kinds of errors as well.

Best regards,

Simon

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Amanda Hsieh — Thu, 26 Mar 2026 16:23:09 GMT

[quote user="Mykhaylo"]Also we have other samples of our custom boards. Some of them work well, but some ones have the same connection issue.[/quote]

If the same code can work on some of your custom boards, but some ones have a connection issue. Then, I would suggest you check the hardware.

Your .pcapng logs show the peripheral side didn't interact with the central.

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Mykhaylo — Thu, 26 Mar 2026 16:00:26 GMT

As I wrote above

If we use nRF54H20-DK the connection is established successfully every time.
If we use our custom board sometimes we get the connection error 8. Both device and app show this error.
Also we have other samples of our custom boards. Some of them work well, but some ones have the same connection issue.

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Amanda Hsieh — Thu, 26 Mar 2026 15:52:59 GMT

Both log-connect-error-8.pcapng and log-connect-error-8-disable-encryption.pcapng show that the peripheral side didn't respond to the central side, which then caused the disconnection.

Are you testing with your app or the NCS samples?

[quote user=""]Also we have other samples of our custom boards. Some of them work well, but some ones have the same connection issue.[/quote]

Does it only happen to the specific custom board? If so, it might be the HW issue. Did you have the PCB reviewed by us? If not, you can create a private case with the title "nRF54H20 PCB review".

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Mykhaylo — Thu, 26 Mar 2026 15:08:29 GMT

This is one more log when connection was established successfully

devzone.nordicsemi.com/.../log_2D00_connect_2D00_without_2D00_error.pcapng

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Mykhaylo — Thu, 26 Mar 2026 15:00:36 GMT

devzone.nordicsemi.com/.../log_2D00_connect_2D00_error_2D00_8_2D00_disable_2D00_encryption.pcapng

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Amanda Hsieh — Thu, 26 Mar 2026 14:41:12 GMT

The communication in the log is encrypted. Could you temporarily disable it and provide the log again?

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Mykhaylo — Thu, 26 Mar 2026 14:06:43 GMT

devzone.nordicsemi.com/.../log_2D00_connect_2D00_error_2D00_8.pcapng

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Amanda Hsieh — Thu, 26 Mar 2026 13:13:31 GMT

Could you provide an nRF Sniffer log? Please capture the log start before the connection.

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Mykhaylo — Thu, 26 Mar 2026 09:24:16 GMT

We added some debug information and see that supervision timeout is 5000ms right after connection. Looks like the value is pretty enough. But the issue (error 8) is still reproduced on some our samples.

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Amanda Hsieh — Wed, 25 Mar 2026 16:54:33 GMT

You can take a look at this DevAcademy course: blefund-lesson-3-exercise-2/

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Mykhaylo — Wed, 25 Mar 2026 15:37:12 GMT

How can we increase supervision timeout?

Mykhaylo

RE: BLE connection issue (error 8) with nRF54H20 + Zephyr

Amanda Hsieh — Wed, 25 Mar 2026 14:59:52 GMT

Hi,

[quote user=""]Also we have other samples of our custom boards. Some of them work well, but some ones have the same connection issue.[/quote]

The disconnect reason 8 is BT_HCI_ERR_CONN_TIMEOUT, which means the supervision timeout. You can refer to those workable samples to increase the supervision timeout.

Regards,
Amanda H.