Flutter/Dart template fails to solve: crossware.app:5050/public-repos/flutter:SDK

Technical Support
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1

I am trying to use the Flutter/Dart template from the Torizon IDE Extension in VS Code on a VirtualBox ubuntu guest connected to a Verdin IMX8MP and all goes well until it tries to pull the docker image from crossware.app:5050/public-repos/flutter:SDK. See the terminal output below.

....skipping a bunch of stuff.....


Applying torizonPackages.json: 
Applying to Dockerfile.debug ...
✅ Dockerfile.debug
Applying to Dockerfile.sdk ...
✅ Dockerfile.sdk
Applying to Dockerfile ...
✅ Dockerfile
torizonPackages.json applied
 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: DOCKER_HOST= docker build --pull -f /home/dev/demo/torizondemo/Dockerfile.sdk /home/dev/demo/torizondemo -t cross-toolchain-arm64-flutter-demo-project --build-arg IMAGE_ARCH=arm64 --build-arg HOST_ARCH=amd64 --build-arg GPU=-imx8 --build-arg APP_ROOT=/home/torizon/app 

[+] Building 21.2s (2/2) FINISHED                                                                                                                                                     docker:default
 => [internal] load build definition from Dockerfile.sdk                                                                                                                                        0.0s
 => => transferring dockerfile: 734B                                                                                                                                                            0.0s
 => ERROR [internal] load metadata for crossware.app:5050/public-repos/flutter:SDK                                                                                                             21.0s
------
 > [internal] load metadata for crossware.app:5050/public-repos/flutter:SDK:
------
Dockerfile.sdk:33
--------------------
  32 |     ##
  33 | >>> FROM --platform=linux/${IMAGE_ARCH} \
  34 | >>>     crossware.app:5050/public-repos/flutter:${SDK_BASE_VERSION}
  35 |     
--------------------
ERROR: failed to build: failed to solve: crossware.app:5050/public-repos/flutter:SDK: failed to resolve source metadata for crossware.app:5050/public-repos/flutter:SDK: failed to do request: Head "https://crossware.app:5050/v2/public-repos/flutter/manifests/SDK": dial tcp 212.47.234.135:5050: connect: connection refused

 *  The terminal process "/usr/bin/bash '-c', 'DOCKER_HOST= docker build --pull -f /home/dev/demo/torizondemo/Dockerfile.sdk /home/dev/demo/torizondemo -t cross-toolchain-arm64-flutter-demo-project --build-arg IMAGE_ARCH=arm64 --build-arg HOST_ARCH=amd64 --build-arg GPU=-imx8 --build-arg APP_ROOT=/home/torizon/app'" terminated with exit code: 1. 
 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: xonsh .conf/validate-deps-running.xsh 


⚠️ VALIDATING ENVIRONMENT

OS:         Linux
OS Version: 7.0.0-30-generic
OS Arch:    x86_64
Under WSL:  false
VS Code:
1.135.0
08d4889f9ec4a1685d257b9b95de036c8e1ce1e5
x64

TOR Extension:  toradex.apollox-vscode@3.7.0

✅ Environment is valid!

 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: bash -c [[ ! -z "10.10.8.38" ]] && true || false 

 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: bash -c [[ "arm64" == "arm64" ]] && true || false 

 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: sshpass -p XXXXremoved scp -P 22 -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o PubkeyAuthentication=no /home/dev/demo/torizondemo/docker-compose.yml torizon@10.10.8.38:~/ 

Warning: Permanently added '10.10.8.38' (ED25519) to the list of known hosts.
 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: /home/dev/demo/torizondemo/.conf/remove-dangling-images.xsh 10.10.8.38:2375 

Waiting for prune lock on host 10.10.8.38:2375
Pruning dangling images on 10.10.8.38:2375
Total reclaimed space: 0B
 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: docker compose -p torizon stop flutter-demo-project flutter-demo-project-debug && docker compose -p torizon rm -f flutter-demo-project flutter-demo-project-debug && sleep 1 

No stopped containers
 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: xonsh /home/dev/demo/torizondemo/.conf/torizon-packages.xsh arm64 

Applying torizonPackages.json: 
Applying to Dockerfile.debug ...
✅ Dockerfile.debug
Applying to Dockerfile.sdk ...
✅ Dockerfile.sdk
Applying to Dockerfile ...
✅ Dockerfile
torizonPackages.json applied
 *  Terminal will be reused by tasks, press any key to close it. 

 *  Executing task: DOCKER_HOST= docker build --pull -f /home/dev/demo/torizondemo/Dockerfile.sdk /home/dev/demo/torizondemo -t cross-toolchain-arm64-flutter-demo-project --build-arg IMAGE_ARCH=arm64 --build-arg HOST_ARCH=amd64 --build-arg GPU=-imx8 --build-arg APP_ROOT=/home/torizon/app 

[+] Building 21.2s (2/2) FINISHED                                                                                                                                                     docker:default
 => [internal] load build definition from Dockerfile.sdk                                                                                                                                        0.0s
 => => transferring dockerfile: 734B                                                                                                                                                            0.0s
 => ERROR [internal] load metadata for crossware.app:5050/public-repos/flutter:SDK                                                                                                             21.0s
------
 > [internal] load metadata for crossware.app:5050/public-repos/flutter:SDK:
------
Dockerfile.sdk:33
--------------------
  32 |     ##
  33 | >>> FROM --platform=linux/${IMAGE_ARCH} \
  34 | >>>     crossware.app:5050/public-repos/flutter:${SDK_BASE_VERSION}
  35 |     
--------------------
ERROR: failed to build: failed to solve: crossware.app:5050/public-repos/flutter:SDK: failed to resolve source metadata for crossware.app:5050/public-repos/flutter:SDK: failed to do request: Head "https://crossware.app:5050/v2/public-repos/flutter/manifests/SDK": dial tcp 212.47.234.135:5050: connect: connection refused

 *  The terminal process "/usr/bin/bash '-c', 'DOCKER_HOST= docker build --pull -f /home/dev/demo/torizondemo/Dockerfile.sdk /home/dev/demo/torizondemo -t cross-toolchain-arm64-flutter-demo-project --build-arg IMAGE_ARCH=arm64 --build-arg HOST_ARCH=amd64 --build-arg GPU=-imx8 --build-arg APP_ROOT=/home/torizon/app'" terminated with exit code: 1. 
 *  Terminal will be reused by tasks, press any key to close it.
2

Hi, I’m the Toradex AI Assistant.

I might make mistakes or occasionally get you wrong. Our support team will step in if needed.

The error indicates that Docker cannot connect to the Crossware registry at crossware.app:5050 to pull the Flutter SDK image. The connection is being refused at 212.47.234.135:5050.

This Flutter/Dart template relies on third-party container images from Crossware, not official Toradex images. The blog post about Flutter on Torizon mentions that Crossware, as a Toradex partner, created a proof-of-concept setup(1), but the template appears to depend on external infrastructure that may be unavailable.

Troubleshooting steps:

  1. Check network connectivity: Verify your VirtualBox Ubuntu guest can reach external registries. Test with:

    curl -v https://crossware.app:5050

  2. Firewall/proxy issues: Corporate networks or firewalls may block port 5050. Ensure outbound connections to this port are allowed(2).

  3. Registry availability: The Crossware registry may be temporarily down or the image may have been moved/removed.

  4. Alternative approach: Since Flutter isn’t officially supported by Toradex templates for production use, consider:

    • Using officially supported templates (Python(3), .NET(4), or C/C++)
    • Building your own Flutter container following the proof-of-concept approach described in the blog(1)
    • Contacting Crossware directly about their registry availability

The Torizon IDE Extension primarily supports official Toradex container images. For third-party templates like Flutter that depend on external registries, you’ll need to ensure those external services are accessible from your development environment.

**

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3

Greetings @dawnhowe_alten,

In your VirtualBox environment where you are running all of this, do you get the same error if you run?: docker pull --platform=linux/arm64 crossware.app:5050/public-repos/flutter:SDK

I just tested this myself and I can pull this Docker container image just fine. Meaning it does exist and the registry serving it is running properly.

If you can’t pull this image, then it seems to be some kind of networking issue between your PC environment and the registry containing the image.

Best Regards,
Jeremias

4

Yes. It turns out that it was blocked by IT networking policy, so the problem was my environment.

Dawn

5

Perfect, glad you were able to isolate the issue on your side and resolve it.

Best Regards,
Jeremias