Diagnose and Fix Mixed Line Endings

When LF Meets CRLF

Mixed line endings occur when a single file contains both LF (\n) and CRLF (\r\n) characters. This typically happens when:

• Multiple developers on different OSes edit the same file
• Text is copy-pasted from different sources
• An editor converts some but not all line endings
• Git's core.autocrlf setting is misconfigured

Detecting the Mix

The Whitespace Visualizer's Line Endings panel reports the exact composition:

Mixed: LF (47), CRLF (3)

This tells you that 47 lines use LF and 3 use CRLF. You can scroll through the visualization to find exactly which lines have the wrong ending — look for the green ←↵ markers among the ↵ markers (or vice versa).

Impact on Git

Git tracks line ending changes as modifications. If your file has mixed endings and you normalize them, Git will show every affected line as changed. This is why it's important to:

1. Normalize early, in a dedicated commit
2. Configure .gitattributes with * text=auto or specific rules
3. Use git add --renormalize . after changing settings

Impact on Tooling

Tool	Symptom
diff / patch	Patches may fail to apply cleanly
linters	ESLint, Prettier may flag or auto-fix endings
compilers	Some compilers or preprocessors choke on mixed endings
Docker	CRLF in COPY'd scripts causes runtime failures

Fixing Mixed Endings

1. Paste the file content into the Whitespace Visualizer.
2. Confirm mixed endings in the Line Endings panel.
3. In Clean, select CRLF (if normalizing to LF) or LF (if normalizing to CRLF).
4. Click Clean and copy the result.

For large projects, configure .gitattributes and run git add --renormalize . to fix all files at once.