🐛 "Request textDocument/codeAction failed" shows when saving JSON files

[CalmProton]

Environment information

$ npx biome rage
CLI:
  Version:                      2.3.6
  Color support:                true

Platform:
  CPU Architecture:             x86_64
  OS:                           windows

Environment:
  BIOME_LOG_PATH:               unset
  BIOME_LOG_PREFIX_NAME:        unset
  BIOME_CONFIG_PATH:            unset
  BIOME_THREADS:                unset
  NO_COLOR:                     unset
  TERM:                         xterm-256color
  JS_RUNTIME_VERSION:           v24.11.1
  JS_RUNTIME_NAME:              node
  NODE_PACKAGE_MANAGER:         npm/11.6.2

Biome Configuration:
  Status:                       Loaded successfully
  Path:                         biome.json
  Formatter enabled:            true
  Linter enabled:               true
  Assist enabled:               true
  VCS enabled:                  true

Workspace:
  Open Documents:               0

What happened?

Whenever saving .vscode/settings.json, it throws this error. It does it all the time, even when no adjustments are made and the file stays the same. Ctrl + S = Getting this error

2025-11-21 20:23:51.934 [info] [Error - 8:23:51 PM] Request textDocument/rangeFormatting failed.
2025-11-21 20:23:51.934 [info]   Message: Biome doesn't support this feature for the language JSONC
  Code: -32603 
Biome doesn't support this feature for the language JSONC//

It is probably what other people in the comments for #6529 refer to.

My biome.json file content - https://pastebin.com/xXDE1a8C
My settings.json file content - https://pastebin.com/MQWY1jU8

Expected result

It should not throw an error.

Code of Conduct

• I agree to follow Biome's Code of Conduct

[ruidosujeira]

VS Code opens settings.json as JSONC, Biome’s LSP claims it supports rangeFormatting, but it doesn’t for JSONC.
VS Code sends the request → Biome throws an error.

Quick workaround:

"[jsonc]": {
  "editor.defaultFormatter": "vscode.json-language-features"
}

or disable Biome for .vscode/**.

Real fix: the server shouldn’t advertise this capability for JSONC or should just return an empty result instead of an error.

[ematipico]

@CalmProton

I believe the real issue is

Biome doesn't support this feature for the language JSONC//

Those slashes in JSONC// are what makes the extension failing, not sure why you have them.

Do you know where it comes from? Did you try setting up JSONC via parser? https://biomejs.dev/reference/configuration/#jsonparserallowcomments

@ruidosujeira

That's not true. Biome even supports biome.jsonc and a variety of known files as JSONC. I admit that the list is obsolete and we should include VSCode settings too.

[ruidosujeira]

@ematipico

thanks for the info. I dug a bit deeper and the // at the end of JSONC// really looks like a VS Code log artifact, nothing coming from Biome itself. However, I noticed that JSONC files (like .vscode/settings.json) were getting a SourceFileNotSupported error when trying to use range formatting (Ctrl+S in VS Code).

While checking this, I saw that FeaturesSupported::with_capabilities() in crates/biome_service/src/workspace.rs only checks whether formatter.format is Some, but ignores format_range and format_on_type.

Is that intentional, or should any of these (format / format_range / format_on_type) be enough to mark FeatureKind::Format as supported for that file type?

[ematipico]

I saw your PR, good catch! Definitley not intentional