Build issue with NCS v1.9.1 using Toolchain v2.0.0

RE: Build issue with NCS v1.9.1 using Toolchain v2.0.0

Priyanka — Mon, 09 Feb 2026 13:09:55 GMT

Hi Praveen,

You can install 2024.12.55 and all nrf extensions from 2024.12

-Priyanka

RE: Build issue with NCS v1.9.1 using Toolchain v2.0.0

Praveen Deshmane — Mon, 09 Feb 2026 01:39:37 GMT

Hello Priyanka,

I have identified a temporary workaround.

By downgrading all nRF-related VS Code extensions, I am now able to see and use the v1.9.1 SDK and toolchain again. The versions currently working are:

2023.9.4 – nRF Connect for VS Code Extension Pack
2023.9.336 – nRF Connect for VS Code
2023.9.57 – nRF DeviceTree
2023.9.94 – nRF Kconfig
2023.9.29 – nRF Terminal

However, based on this behavior, it appears that in the latest VS Code extension releases, support for displaying and using the v1.9.1 toolchain has been removed or deprecated.

Could you please confirm whether this is the expected behavior and if there is an official recommendation for users who still need to work with SDK v1.9.1 and toolchain?

Thank you.

- Praveen Deshmane

RE: Build issue with NCS v1.9.1 using Toolchain v2.0.0

Priyanka — Fri, 06 Feb 2026 14:00:42 GMT

Hi Praveen,

I am able to replicate the issue on my end as well and I am checking this internally. I will update you regarding this.

-Priyanka

RE: Build issue with NCS v1.9.1 using Toolchain v2.0.0

Praveen Deshmane — Fri, 06 Feb 2026 00:28:44 GMT

Hello Priyanka,

Recently, the nRF Connect for VS Code extension was automatically updated to version 2026.1.1327. Since this update, we are no longer able to see or select the v1.9.1 toolchain. The extension displays “Install Toolchain to get started”, and when selecting Install Toolchain, only toolchain versions from v3.2.1 down to v2.0.0 are available. There is no option to install or select v1.9.1.

Due to this limitation, I installed the v2.0.0 toolchain and attempted to build and flash our application using it. However, the build and flashing process was unsuccessful.

As per your previous guidance recommending the use of matching SDK and toolchain versions, this means our application cannot be built unless we migrate from SDK v1.9.1 to v2.0.0. At present, we do not have plans to migrate to v2.0.0, as this would require significant changes to the application source code and considerable development time.

Currently, we are facing an issue on our production terminals (devices), and in order to investigate the root cause, we need to analyze the terminal logs using our development environment. However, since we are unable to build the development environment with SDK v1.9.1 (vs code extension issue), this investigation is blocked.

Given the impact on production issue analysis, we kindly request your urgent support on this matter and guidance on how to proceed as soon as possible.

Is there any way to continue using the v1.9.1 toolchain?

Thank you for your support.

- Praveen Deshmane

RE: Build issue with NCS v1.9.1 using Toolchain v2.0.0

Priyanka — Thu, 05 Feb 2026 11:25:58 GMT

Hi Praveen,

I will check this internally. In the meantime, could you tell me whether you face any significant issues when working with SDK v1.9.1 + toolchain v1.9.1?

-Priyanka

RE: Build issue with NCS v1.9.1 using Toolchain v2.0.0

Praveen Deshmane — Thu, 05 Feb 2026 00:13:16 GMT

Hello Priyanka,

Thank you for your response.

Migrating from NCS v1.9.1 to v2.0.0 would require significant changes to the application source code.

Is there any way to continue using the v1.9.1 toolchain?

- Praveen

RE: Build issue with NCS v1.9.1 using Toolchain v2.0.0

Priyanka — Wed, 04 Feb 2026 09:14:14 GMT

Hi Praveen,

We generally recommend using the same SDK and Toolchain versions. So please try using SDK v2.0.0

Please take a look at the following migration guide to transition from SDK 1.x.x to 2.x.x

https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/releases_and_maturity/migration/migration_guide_1.x_to_2.x.html

-Priyanka