When formatting a file that has extension of A but it is actually language B (and selected as so in Vs Code), prettier still formats it as language A and errors out.
Prettier formats the document as HTML.
Prettier extension errors out because it ignores the Language Mode and still tries to format it as JSON.
["INFO" - 11:39:48 AM] Extension Name: esbenp.prettier-vscode.
["INFO" - 11:39:48 AM] Extension Version: 11.0.0.
["INFO" - 11:39:56 AM] Formatting file:///c%3A/files/codtest/html.json
["INFO" - 11:39:56 AM] PrettierInstance:
{
"doc": {
"builders": {
"line": {
"type": "line"
},
"softline": {
"type": "line",
"soft": true
},
"hardline": {
"type": "concat",
"parts": [
{
"type": "line",
"hard": true
},
{
"type": "break-parent"
}
]
},
"literalline": {
"type": "concat",
"parts": [
{
"type": "line",
"hard": true,
"literal": true
},
{
"type": "break-parent"
}
]
},
"lineSuffixBoundary": {
"type": "line-suffix-boundary"
},
"cursor": {
"type": "cursor"
},
"breakParent": {
"type": "break-parent"
},
"trim": {
"type": "trim"
},
"hardlineWithoutBreakParent": {
"type": "line",
"hard": true
},
"literallineWithoutBreakParent": {
"type": "line",
"hard": true,
"literal": true
}
},
"printer": {},
"utils": {},
"debug": {}
},
"version": "2.8.8",
"util": {},
"__internal": {
"errors": {},
"coreOptions": {
"CATEGORY_CONFIG": "Config",
"CATEGORY_EDITOR": "Editor",
"CATEGORY_FORMAT": "Format",
"CATEGORY_OTHER": "Other",
"CATEGORY_OUTPUT": "Output",
"CATEGORY_GLOBAL": "Global",
"CATEGORY_SPECIAL": "Special",
"options": {
"cursorOffset": {
"since": "1.4.0",
"category": "Special",
"type": "int",
"default": -1,
"range": {
"start": -1,
"end": null,
"step": 1
},
"description": "Print (to stderr) where a cursor at the given position would move to after formatting.\nThis option cannot be used with --range-start and --range-end.",
"cliCategory": "Editor"
},
"endOfLine": {
"since": "1.15.0",
"category": "Global",
"type": "choice",
"default": [
{
"since": "1.15.0",
"value": "auto"
},
{
"since": "2.0.0",
"value": "lf"
}
],
"description": "Which end of line characters to apply.",
"choices": [
{
"value": "lf",
"description": "Line Feed only (\\n), common on Linux and macOS as well as inside git repos"
},
{
"value": "crlf",
"description": "Carriage Return + Line Feed characters (\\r\\n), common on Windows"
},
{
"value": "cr",
"description": "Carriage Return character only (\\r), used very rarely"
},
{
"value": "auto",
"description": "Maintain existing\n(mixed values within one file are normalised by looking at what's used after the first line)"
}
]
},
"filepath": {
"since": "1.4.0",
"category": "Special",
"type": "path",
"description": "Specify the input filepath. This will be used to do parser inference.",
"cliName": "stdin-filepath",
"cliCategory": "Other",
"cliDescription": "Path to the file to pretend that stdin comes from."
},
"insertPragma": {
"since": "1.8.0",
"category": "Special",
"type": "boolean",
"default": false,
"description": "Insert @format pragma into file's first docblock comment.",
"cliCategory": "Other"
},
"parser": {
"since": "0.0.10",
"category": "Global",
"type": "choice",
"default": [
{
"since": "0.0.10",
"value": "babylon"
},
{
"since": "1.13.0"
}
],
"description": "Which parser to use.",
"choices": [
{
"value": "flow",
"description": "Flow"
},
{
"value": "babel",
"since": "1.16.0",
"description": "JavaScript"
},
{
"value": "babel-flow",
"since": "1.16.0",
"description": "Flow"
},
{
"value": "babel-ts",
"since": "2.0.0",
"description": "TypeScript"
},
{
"value": "typescript",
"since": "1.4.0",
"description": "TypeScript"
},
{
"value": "acorn",
"since": "2.6.0",
"description": "JavaScript"
},
{
"value": "espree",
"since": "2.2.0",
"description": "JavaScript"
},
{
"value": "meriyah",
"since": "2.2.0",
"description": "JavaScript"
},
{
"value": "css",
"since": "1.7.1",
"description": "CSS"
},
{
"value": "less",
"since": "1.7.1",
"description": "Less"
},
{
"value": "scss",
"since": "1.7.1",
"description": "SCSS"
},
{
"value": "json",
"since": "1.5.0",
"description": "JSON"
},
{
"value": "json5",
"since": "1.13.0",
"description": "JSON5"
},
{
"value": "json-stringify",
"since": "1.13.0",
"description": "JSON.stringify"
},
{
"value": "graphql",
"since": "1.5.0",
"description": "GraphQL"
},
{
"value": "markdown",
"since": "1.8.0",
"description": "Markdown"
},
{
"value": "mdx",
"since": "1.15.0",
"description": "MDX"
},
{
"value": "vue",
"since": "1.10.0",
"description": "Vue"
},
{
"value": "yaml",
"since": "1.14.0",
"description": "YAML"
},
{
"value": "glimmer",
"since": "2.3.0",
"description": "Ember / Handlebars"
},
{
"value": "html",
"since": "1.15.0",
"description": "HTML"
},
{
"value": "angular",
"since": "1.15.0",
"description": "Angular"
},
{
"value": "lwc",
"since": "1.17.0",
"description": "Lightning Web Components"
}
]
},
"plugins": {
"since": "1.10.0",
"type": "path",
"array": true,
"default": [
{
"value": []
}
],
"category": "Global",
"description": "Add a plugin. Multiple plugins can be passed as separate `--plugin`s.",
"cliName": "plugin",
"cliCategory": "Config"
},
"pluginSearchDirs": {
"since": "1.13.0",
"type": "path",
"array": true,
"default": [
{
"value": []
}
],
"category": "Global",
"description": "Custom directory that contains prettier plugins in node_modules subdirectory.\nOverrides default behavior when plugins are searched relatively to the location of Prettier.\nMultiple values are accepted.",
"cliName": "plugin-search-dir",
"cliCategory": "Config"
},
"printWidth": {
"since": "0.0.0",
"category": "Global",
"type": "int",
"default": 80,
"description": "The line length where Prettier will try wrap.",
"range": {
"start": 0,
"end": null,
"step": 1
}
},
"rangeEnd": {
"since": "1.4.0",
"category": "Special",
"type": "int",
"default": null,
"range": {
"start": 0,
"end": null,
"step": 1
},
"description": "Format code ending at a given character offset (exclusive).\nThe range will extend forwards to the end of the selected statement.\nThis option cannot be used with --cursor-offset.",
"cliCategory": "Editor"
},
"rangeStart": {
"since": "1.4.0",
"category": "Special",
"type": "int",
"default": 0,
"range": {
"start": 0,
"end": null,
"step": 1
},
"description": "Format code starting at a given character offset.\nThe range will extend backwards to the start of the first line containing the selected statement.\nThis option cannot be used with --cursor-offset.",
"cliCategory": "Editor"
},
"requirePragma": {
"since": "1.7.0",
"category": "Special",
"type": "boolean",
"default": false,
"description": "Require either '@prettier' or '@format' to be present in the file's first docblock comment\nin order for it to be formatted.",
"cliCategory": "Other"
},
"tabWidth": {
"type": "int",
"category": "Global",
"default": 2,
"description": "Number of spaces per indentation level.",
"range": {
"start": 0,
"end": null,
"step": 1
}
},
"useTabs": {
"since": "1.0.0",
"category": "Global",
"type": "boolean",
"default": false,
"description": "Indent with tabs instead of spaces."
},
"embeddedLanguageFormatting": {
"since": "2.1.0",
"category": "Global",
"type": "choice",
"default": [
{
"since": "2.1.0",
"value": "auto"
}
],
"description": "Control how Prettier formats quoted code embedded in the file.",
"choices": [
{
"value": "auto",
"description": "Format embedded code if Prettier can automatically identify it."
},
{
"value": "off",
"description": "Never automatically format embedded code."
}
]
}
}
},
"optionsModule": {
"hiddenDefaults": {
"astFormat": "estree",
"printer": {},
"locStart": null,
"locEnd": null
}
},
"optionsNormalizer": {},
"utils": {}
},
"__debug": {}
}
["INFO" - 11:39:56 AM] Using ignore file (if present) at c:\files\codtest\.prettierignore
["INFO" - 11:39:56 AM] File Info:
{
"ignored": false,
"inferredParser": "json"
}
["INFO" - 11:39:56 AM] No local configuration (i.e. .prettierrc or .editorconfig) detected, falling back to VS Code configuration
["INFO" - 11:39:56 AM] Prettier Options:
{
"arrowParens": "always",
"bracketSpacing": true,
"endOfLine": "lf",
"htmlWhitespaceSensitivity": "css",
"insertPragma": false,
"singleAttributePerLine": false,
"bracketSameLine": false,
"jsxBracketSameLine": false,
"jsxSingleQuote": false,
"printWidth": 80,
"proseWrap": "preserve",
"quoteProps": "as-needed",
"requirePragma": false,
"semi": true,
"singleQuote": false,
"tabWidth": 2,
"trailingComma": "es5",
"useTabs": false,
"embeddedLanguageFormatting": "auto",
"vueIndentScriptAndStyle": false,
"experimentalTernaries": false,
"filepath": "c:\\files\\codtest\\html.json",
"parser": "json"
}
["ERROR" - 11:39:56 AM] Error formatting document.
["ERROR" - 11:39:56 AM] Unexpected token (2:1)
1 |
> 2 | <!doctype html>
| ^
3 | <html>
4 | <head>
5 | <title>Example Domain</title>
SyntaxError: Unexpected token (2:1)
1 |
> 2 | <!doctype html>
| ^
3 | <html>
4 | <head>
5 | <title>Example Domain</title>
at p (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\parser-babel.js:22:1054)
at d (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\parser-babel.js:22:1287)
at Object.parse (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\parser-babel.js:29:51283)
at Object.parse (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\index.js:7515:23)
at coreFormat (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\index.js:8829:18)
at formatWithCursor2 (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\index.js:9021:18)
at c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\index.js:38183:12
at Object.format (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\node_modules\prettier\index.js:38197:12)
at t.default.format (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\dist\extension.js:1:16369)
at t.PrettierEditProvider.provideEdits (c:\Users\ikena\.vscode-insiders\extensions\esbenp.prettier-vscode-11.0.0\dist\extension.js:1:12927)
at oD.provideDocumentFormattingEdits (file:///c:/Users/ikena/AppData/Local/Programs/Microsoft%20VS%20Code%20Insiders/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:140:137286)
["INFO" - 11:39:56 AM] Formatting completed in 38ms.
Summary
When formatting a file that has extension of A but it is actually language B (and selected as so in Vs Code), prettier still formats it as language A and errors out.
Steps To Reproduce:
Save it to
html.json.ctrl+shift+Pthen search "language mode"), and choose HTML.Expected result
Prettier formats the document as HTML.
Actual result
Prettier extension errors out because it ignores the Language Mode and still tries to format it as JSON.
You can see it clearly in the log because it says
"parser": "json".Additional information
VS Code Version:
Version: 1.104.0-insider (user setup)
Commit: 5d24d0fea3ffc65b824989dda916714a46ca97a7
Date: 2025-08-19T05:03:18.690Z
Electron: 37.2.3
ElectronBuildId: 12035395
Chromium: 138.0.7204.100
Node.js: 22.17.0
V8: 13.8.500258-electron.0
OS: Windows_NT x64 10.0.19045
Prettier Extension Version:
11.0.0
OS and version:
Windows 10 x64
Prettier Log Output