VS Code axe Accessibility Linter fails to start

[ChipElavon]

Product: axe Linter

Expectation: Linter extension starts

Actual:

• On first run errors popups "Unable to start axe-linter" and "Unable to download local-server" appear.
• After restarting VSCode the error popups change to "Unable to start axe-linter" and "Unable to start local-server".
• If I chmod +x ~/.vscode/extensions/deque-systems.vscode-axe-linter-4.4.0/bin/axe-linter-server-4.4.0-macos and restart VSCode I get a popup "axe Linter setup: Starting local-server" that never progresses/finishes
  • running ./axe-linter-server-4.4.0-macos directly in the terminal prints no output and gives an exit code 0
  • investigating further ~/.vscode/extensions/deque-systems.vscode-axe-linter-4.4.0/bin/axe-linter-server-4.4.0-macos is 0 bytes in size so that explains why nothing is happening

axe-linter version: 4.4.0
vscode about output:
  Version: 1.67.2 (Universal)
  Commit: c3511e6c69bb39013c4a4b7b9566ec1ca73fc4d5
  Date: 2022-05-17T18:20:57.384Z (6 days ago)
  Electron: 17.4.1
  Chromium: 98.0.4758.141
  Node.js: 16.13.0
  V8: 9.8.177.13-electron.0
  OS: Darwin x64 21.3.0

For Tooling issues:
- Platform:  macOS 12.2.1

I'm on a machine with corporate controls installed and behind a restrictive firewall and one of those facts is probably interfering with the extension working, but I'm not finding much information to go on to figure out what exactly is going wrong with the extension starting up or what local-server it's trying and failing to download.

Looking for some help to get this extension working so we can fix a11y issues earlier in the development cycle.

Screenshot of what I see right after I install the linter extension:

[straker]

Thanks for the issue. We've been working on some major improvements to the linter that should fix some of the download issues. We're hoping to have it released in the next quarter or two.

[straker]

@ChipElavon We recently released a new version of axe linter (v4.4.1) that should address this issue. Would you be willing to give it another go and let us know if you run into any more issues?

[dstorfer-cn]

@ChipElavon We recently released a new version of axe linter (v4.4.1) that should address this issue. Would you be willing to give it another go and let us know if you run into any more issues?

I'm running into an issue with the new version 4.4.1. I get a popup saying "Couldn't start client axe Linter" and here is my OUTPUT window contents:

[Error - 3:42:43 PM] Starting client failed
Error: spawn UNKNOWN
	at ChildProcess.spawn (node:internal/child_process:412:11)
	at Object.spawn (node:child_process:718:9)
	at c:\Users\CN123456\.vscode\extensions\deque-systems.vscode-axe-linter-4.4.1\dist\src\extension.js:2:226632

This doesn't seem like a download issue like the firewall one that I had before. I managed to solve the download issue by figuring out how to trick the firewall, manually download the files, and put them where they needed to be. But this error looks more internal to either node or the plugin.

[ChipElavon]

@ChipElavon We recently released a new version of axe linter (v4.4.1) that should address this issue. Would you be willing to give it another go and let us know if you run into any more issues?

I tried today and got the following error message after installing the extension and restarting VSCode:

[Error - 1:27:24 PM] Starting client failed
Error: spawn Unknown system error -8
    at ChildProcess.spawn (node:internal/child_process:412:11)
    at Object.spawn (node:child_process:718:9)
    at /Users/m183/.vscode/extensions/deque-systems.vscode-axe-linter-4.4.1/dist/src/extension.js:2:226632

[cms365]

@ChipElavon We recently released a new version of axe linter (v4.4.1) that should address this issue. Would you be willing to give it another go and let us know if you run into any more issues?

I tried today and got the following error message after installing the extension and restarting VSCode:

[Error - 1:27:24 PM] Starting client failed
Error: spawn Unknown system error -8
    at ChildProcess.spawn (node:internal/child_process:412:11)
    at Object.spawn (node:child_process:718:9)
    at /Users/m183/.vscode/extensions/deque-systems.vscode-axe-linter-4.4.1/dist/src/extension.js:2:226632

Seeing this exact issue as well. Following.

[gps03]

Seeing the same error:

[Error - 2:23:17 PM] Starting client failed
Error: spawn Unknown system error -8
at ChildProcess.spawn (node:internal/child_process:441:11)
at Object.spawn (node:child_process:752:9)
at /Users/gps03/.vscode/extensions/deque-systems.vscode-axe-linter-4.7.2/dist/src/extension.js:1:250750
at processTicksAndRejections (node:internal/process/task_queues:96:5)

But also seeing a popup error "unable to get issuer certificate"

[mamankhan99]

+1

on Node 20.9.0 and axe accessibility linter 4.8.0

[jsdev]

there is a strong chance you need to do the following 3 things:
in .vscode/settings.json add:
"telemetry.telemetryLevel": "off"
chmod +x ~/.vscode/extensions/deque-systems.vscode-axe-lineter-[version.num.ber]

3rd step might be providing an alternative to axe-linter-server-binary-prod-[resion].s3.amazonaws.com

[jeremy-w]

I believe this is caused by not supporting a tunneling HTTPS proxy when making the requests. Making the same requests using curl in a properly configured shell environment works fine.

Recommended Fix

The fix I'd recommend making to axe-core is to pull in the package proxy-agent and then to turn off Axios's own, limited proxy support in favor of using that package's agent as the httpsAgent:

const agent = new ProxyAgent();
axios = axios.create({proxy: false, httpAgent: agent, httpsAgent: agent});

(See https://stackoverflow.com/a/62277342.)

Node unfortunately does not support tunneling proxies out of the box. See the discussion in nodejs/node issue #15620 http: deal with the lack of http proxy support in node.js core.

Workaround

Assuming you have the extension installed already, and you're running under macOS, this should work:

# Find the version of the binary we need, and move into that extension folder
cd "$(ls -d ~/.vscode/extensions/deque-systems.vscode-axe-linter-* | sort -rn | head -1)"
VERSION="$(basename "$(pwd)" | awk -F- '{print $NF}')"

# Download that binary and make it executable
cd dist/bin/
curl https://axe-linter-server-binary-prod-us-east-1.s3.amazonaws.com/$VERSION/lsp-server-macos -o LSP-server-$VERSION
chmod 775 LSP-server-*

# Create a file that axe-core expects to find, so it doesn't try to re-download the binary and zero it out again on you
binSize=$(curl -sI https://axe-linter-server-binary-prod-us-east-1.s3.amazonaws.com/$VERSION/lsp-server-macos | grep Content-Length | awk '{print $2}')
echo '{"binSize": '$binSize', "downloaded": true}' > ../lsp-bin-information

But you'll need to re-run this snippet whenever the extension version updates, because it'll try to grab the new version and fail.

[ChipElavon]

Thanks @jeremy-w that workaround fixes the issue for me. I'll leave this open until the fix is in the plugin itself and a workaround is no longer needed, but at least I can use the plugin now.

[Lanie-Carmelo]

I'm on Windows and experiencing this issue:
[Error - 9:33:57 AM] Starting client failed
Error: spawn UNKNOWN
at ChildProcess.spawn (node:internal/child_process:421:11)
at Object.spawn (node:child_process:796:9)
at c:\Users\lgcar.vscode\extensions\deque-systems.vscode-axe-linter-4.10.1\dist\src\extension.js:2:264354
Axe isn't vital for me yet since I'm just learning to code, but I do like to have it to help me catch accessibility issues. How can I fix this?

[WilcoFiers]

@Lanie-Carmelo thanks for reporting. I'll get someone to investigate. The error isn't too informative, so we may have further questions. Did you have axe linter installed before, or was this a new install you did?

[drmenzelit]

Having the same problem here since a couple of days. Windows 11, Visual Studio Code 1.95.3, axe Linter 4.10.1. It was working previously without problems.

[Error - 12:56:46] Starting client failed Error: spawn UNKNOWN at ChildProcess.spawn (node:internal/child_process:421:11) at Object.spawn (node:child_process:796:9) at c:\Users\xxxx\.vscode\extensions\deque-systems.vscode-axe-linter-4.10.1\dist\src\extension.js:2:264354

[WilcoFiers]

We think we've identified the issue, but so close to US holidays we didn't want to chance it. We've reverted to axe linter 4.10.0 and have re-released it axe 4.10.2. Please upgrade to 4.10.2 to solve this issue. That should solve any issues. We'll work on getting the changes promised in 4.10.1 released next week and will get these out as soon as possible. We'll also be sure to tighten up the release process so that this can never happen again. Our apologies for any inconvenience.

If anyone does still have issues with the latest install (can't think why, but who knows), please let us know in the thread.

[Lanie-Carmelo]

Just got a chance to test things since I'm working on another project, and I'm seeing this:
[Error - 12:09:46 AM] Starting client failed
Error: spawn EBUSY
at ChildProcess.spawn (node:internal/child_process:421:11)
at Object.spawn (node:child_process:796:9)
at c:\Users\lgcar.vscode\extensions\deque-systems.vscode-axe-linter-4.10.2\dist\src\extension.js:2:264354

[WilcoFiers]

@Lanie-Carmelo thanks for reporting, we're investigating.

[thomasvanlankveld]

Fresh install of the axe Accessibility linter v4.10.2 gives me a toast with "Couldn't start client axe Linter", and the following output:

[Error - 11:29:31] Starting client failed
Error: spawn Unknown system error -86
	at ChildProcess.spawn (node:internal/child_process:421:11)
	at Object.spawn (node:child_process:776:9)
	at /Users/<path>/.cursor/extensions/deque-systems.vscode-axe-linter-4.10.2/dist/src/extension.js:2:264354

[WilcoFiers]

@thomasvanlankveld Thank you for reporting. If you restart, does the issue persist? If not, can you try uninstalling axe linter and reinstalling?

[robinloeffel]

I'm getting the same error, but on macOS.

[Error - 17:16:02] Starting client failed
Error: spawn Unknown system error -86
	at ChildProcess.spawn (node:internal/child_process:420:11)
	at Object.spawn (node:child_process:796:9)
	at /Users/robin/.vscode/extensions/deque-systems.vscode-axe-linter-4.10.2/dist/src/extension.js:2:264354

It persists after restarting the extensions manually, and also after reinstalling Axe Linter.

[michael-siek]

Hey @robinloeffel do you mind checking this path to see what the size of the binary is? It might be an issue with getting the binary from aws if you have a strict firewall policy

~/.vscode/extensions/deque-systems.vscode-axe-linter-4.10.2/dist/bin/LSP-server-4.10.2