Failed to parse `pyproject.toml` error when pyproject.toml has comments and CRLF line endings

[joelspadin]

Environment data

• Pylance version: 2026.1.1
• OS and version: Windows 11 build 26200
• Python version (& distribution if applicable, e.g. Anaconda): 3.14.2

Code Snippet

[tool.ruff.lint]
select = [
  # flake8-builtins
  "A"
]

Repro Steps

Create a pyproject.toml, set line endings to CRLF, then simply add a comment anywhere. The Python logs in the output panel will then log an error like this:

2026-02-21 16:17:12.732 [error] Failed to parse `pyproject.toml`: [TomlError: Control characters (codes < 0x1f and 0x7f) are not allowed in comments, use \u000d instead at row 28, col 20, pos 620:
27: select = [
28>   # flake8-builtins
                       ^
29:   "A",


	at i.errorControlCharIn (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:1109372)
	at i.parseComment (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:1101920)
	at i.runOne (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:1093896)
	at i.parse (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:1093642)
	at e.exports (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:1127199)
	at E (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:802534)
	at t.isPipInstallableToml (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:802782)
	at s (c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:806995)
	at c:\Users\Joel\.vscode\extensions\ms-python.python-2026.2.0-win32-x64\out\client\extension.js:2:807364
	at ef.value (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:213:103000)
	at I.C (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2328)
	at I.D (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2398)
	at I.fire (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2615)
	at JZ.$acceptModelSaved (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:144:125565)
	at LE.S (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:125501)
	at LE.Q (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:125281)
	at LE.M (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:124370)
	at LE.L (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:123475)
	at ef.value (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:122272)
	at I.C (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2328)
	at I.fire (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2546)
	at Jo.fire (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9471)
	at ef.value (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:405:9337)
	at I.C (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2328)
	at I.fire (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2546)
	at Jo.fire (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9471)
	at MessagePortMain.<anonymous> (file:///c:/Users/Joel/AppData/Local/Programs/Microsoft%20VS%20Code/072586267e/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:405:7571)
	at MessagePortMain.emit (node:events:519:28)
	at MessagePortMain._internalPort.emit (node:electron/js2c/utility_init:2:2959)] {
  fromTOML: true,
  wrapped: null,
  line: 27,
  col: 19,
  pos: 620
}

Switching the line ending to LF prevents this error from showing in the logs.

[github-actions]

Hi @joelspadin, I'm an AI Support assistant here to help with your issue. While the team reviews your request, I wanted to provide some possible tips and documentation that might help you in the meantime.

---

Explanation:

• The TOML parser reports an error on control characters found in comments when files use CRLF line endings, interpreting the carriage return as an invalid control character.
• Converting the file to LF-only line endings removes the carriage return, preventing parse errors when comments are present.

---

Potential Duplicate Issues – These issues may be duplicates of your report, but may differ in some of the details.

• Ensure that comments in TOML files use the correct line endings and do not contain unsupported control characters to avoid parse errors. TOML 1.0.0 parser used in latest release 1.1.285 fails to parse line endings of comments pyright#4367

---

Potential Workarounds:

• Enforce LF (\n) line endings for pyproject.toml (for example, via your editor settings or a .gitattributes file) to avoid carriage return control characters.
• Temporarily remove or relocate comments in pyproject.toml if changing line endings is not feasible.

---

The team will respond to your issue shortly. Please note this is a trial feature and may not be fully accurate. I hope these suggestions are helpful in the meantime. If this comment helped you, please give it a 👍. If the suggestion was not helpful or was incorrect, please give it a 👎. Your feedback helps us improve!

[rchiodo]

The callstack you're showing is for the Python extension, not Pylance. Transferring.