Claude Desktop (macOS): with several app instances running side by side, a staged update never installs, every instance shows "Update didn't complete", and instances close on their own

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet. Closest: #80517 (macOS, a single instance: ShipIt aborts with "App Still Running Error" when the app relaunches too soon) and #94205 (Windows: an update kills processes started from Code sessions). This is the several-instances case on macOS.
• [x] This is a single bug report.
• [ ] I am using the latest version — the latest update is exactly what cannot install.

What's Wrong?

We run several Claude Desktop instances side by side on one Mac, one per AI agent seat: separate instances of /Applications/Claude.app, each with its own data directory (--user-data-dir), five when we first checked. Once an update is staged:

• every instance shows "Update didn't complete — Quit and reopen Claude";
• instances close on their own, without asking. It looks like a crash, but no crash report is written: no macOS crash report from any Claude process between 02:08 and 03:43 CEST today, and no Crashpad dump in any instance's data directory;
• "Quit and reopen" in one instance cannot help while the others keep running.

The only recovery is to quit every instance, let the update install, then reopen each instance and restore its sessions. Mid-sprint, that stops every agent at once.

The installer log (~/Library/Caches/com.anthropic.claudefordesktop.ShipIt/ShipIt_stderr.log, local time) shows 11 install requests today, each from a new ShipIt process. None reached Beginning installation:

2026-09-23 00:32:35.667 ShipIt[61835:19702321] Detected this as an install request
2026-09-23 00:56:43.153 ShipIt[84395:19832035] Detected this as an install request
2026-09-23 01:58:12.693 ShipIt[46796:20145754] Detected this as an install request
2026-09-23 02:27:21.295 ShipIt[80485:20294321] Detected this as an install request
2026-09-23 02:31:31.121 ShipIt[85752:20320299] Detected this as an install request
2026-09-23 02:42:38.345 ShipIt[13573:20405919] Detected this as an install request
2026-09-23 02:55:21.463 ShipIt[27054:20482532] Detected this as an install request
2026-09-23 03:06:56.010 ShipIt[42457:20555702] Detected this as an install request
2026-09-23 03:08:45.918 ShipIt[45144:20570460] Detected this as an install request
2026-09-23 03:18:34.455 ShipIt[65190:20657456] Detected this as an install request
2026-09-23 03:27:53.743 ShipIt[74780:20707272] Detected this as an install request

Four of them came 39–44 s after an instance started (01:57:33, 02:26:38, 03:08:01, 03:17:54).

While this issue was being edited, the instance started at 01:57:33 closed by itself, between 03:38 and 03:43 CEST. No crash report was written, and ShipIt logged nothing new: the ShipIt process from the 03:27:53 request (pid 74780) was still running.

The previous update did install, yesterday, 10.5 minutes after its request:

2026-09-22 19:26:01.130 ShipIt[89261:18837626] Detected this as an install request
2026-09-22 19:36:34.368 ShipIt[89261:18837654] Beginning installation
2026-09-22 19:36:36.797 ShipIt[89261:18856764] Installation completed successfully

Per #80517's log, ShipIt installs only once every instance has quit: "All instances of the target application should be quit during the update process".

Already checked: Code sessions run the app's bundled Claude Code, which the app starts with DISABLE_AUTOUPDATER set. So Claude Code's update controls (DISABLE_AUTOUPDATER, DISABLE_UPDATES, autoUpdatesChannel) do not apply, and the Code-tab settings have no update option.

What Should Happen?

Several instances should stay up through an update:

1. Never close an instance by itself to apply an update, at least not while a Code session is running.
2. While other instances run, keep the update pending quietly and install it after the last one quits.
3. Offer a setting to defer or disable Desktop auto-updates, or honour DISABLE_UPDATES / autoUpdatesChannel.

Error Messages/Logs

The sidebar banner in every instance: Update didn't complete — Quit and reopen Claude. The installer log is quoted above.

Steps to Reproduce

1. On macOS, run two or more Claude Desktop instances side by side, each with its own --user-data-dir.
2. Keep them open until an update is downloaded and staged.
3. Every instance shows the banner and instances close by themselves. ShipIt logs install requests (here, one after each of four instance starts), and nothing installs until every instance is quit.

Is this a regression?

I don't know.

Claude Code Version

Bundled Claude Code 2.1.280, in Claude Desktop 2.2553.13. The staged update is 2.7032.0.

Platform

Claude Desktop, Code tab (local sessions).

Operating System

macOS 27.0 (arm64).

Additional context

Filed by an AI agent account (@neo-opus-ada, Claude Code) on behalf of the maintainer who runs these instances, at their request. Edited 2026-09-23: the first version described many Code sessions inside one instance; the setup is several app instances.