Crash on macOS 15.x when rendering rename-only diff in Diff view (NSAttributedString range exception)

[chenin]

Environment

• App: GitUp 1.4.3 (1052)
• OS: macOS 15.7.3 (24G419)
• Architecture: x86_64 (Intel)
• Hardware: MacBookPro16,2

Summary

GitUp intermittently crashes on macOS 15.x when performing a rename-only operation and GitUp attempts to render the diff.
The crash occurs on the main thread while rendering the Diff view and is caused by an uncaught Objective-C exception inside NSConcreteMutableAttributedString.

This is not a Git repository corruption issue and does not occur when using git directly in the terminal.

Crash signature

The crash is consistent across multiple reports and always shows the same backtrace:

• Foundation -[NSMutableRLEArray replaceObjectsInRange:withObject:length:] -[NSConcreteMutableAttributedString setAttributes:range:]
• GitUpKit -[GIDiffContentsViewController tableView:viewForTableColumn:row:]
• AppKit -[NSApplication _crashOnException:]

The process terminates with EXC_BAD_INSTRUCTION (SIGILL) after AppKit forcefully aborts due to the uncaught exception.

Key observations

• The operation is a rename-only change (no content changes).
• The rename frequently involves files under a dot-prefixed directory (e.g. .Inbox), but the directory name itself is not required to trigger the crash.
• The issue does not occur every time. It appears to depend on the Diff view state and timing.
• The crash happens when GitUp refreshes or renders the Diff view after the rename.
• The same rename operation works reliably using git mv + git commit in the terminal.

This suggests a UI rendering issue rather than a Git data issue.

[lucasderraugh]

How are you performing the rename? I assume it's outside of GitUp?

[chenin]

Yes, the rename is performed outside of GitUp.

I have reproduced the issue by renaming the file both in Zed and in Finder.
For example, a file located at:

~/Documents/Corpus/.Inbox/待办事项.md

is renamed to:

~/Documents/Corpus/.Inbox/待办事项_.md

After this rename, when GitUp refreshes and I open the Commit / Diff view to inspect the change, GitUp may crash while rendering the diff. In my case, the crash happens after clicking “Stage All”, when GitUp updates and displays the staged diff.

The Git repository itself is located at ~/Documents/Corpus/.git.

[chenin]

Additional observation:

The crash appears to depend on how the new filename is formed. When the original filename contains non-ASCII characters (e.g. Chinese), adding extra characters to that name consistently triggers the crash.

For example, starting from:

中文命名.md

The following renames crash GitUp reliably when viewing the staged diff:

中文命名.md → 中文命名1.md

中文命名.md → 中文命名 - 其它.md

However, renaming the file to a completely different name does not trigger the crash:

中文命名.md → 其它命名.md

[lucasderraugh]

Thanks, I assumed the name mattered in this way as when ranges are wrong like that it's usually something with assuming strings of a certain length. I'll see if I get some time over the holidays to finally get out a release I've been needing to patch macOS Tahoe with.

[chenin]

I really appreciate you taking the time to look into it.
Wishing you a great holiday period, and I’m looking forward to the next release whenever it’s ready.

[lucasderraugh]

Should be all fixed in master. Will probably kick out a release soon after I test some more of my Tahoe changes.