### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet - [x] This is a single bug report (please file separate reports for different bugs) - [x] I am using the latest version of Claude Code ### What's Wrong? What's Wrong? Every conversation creates a new user directory under /sessions/ / inside the VM and caches all installed plugins there. These

[BUG] Cowork Plugin cache never cleaned up per session, causing sessiondata.img to fill up and all new conversations to fail

Status Closed — not planned

Maintainer reply None cached

Activity 10 comments · opened Mar 4, 2026 · closed May 24, 2026

Preflight Checklist

[x] I have searched existing issues and this hasn't been reported yet
[x] This is a single bug report (please file separate reports for different bugs)
[x] I am using the latest version of Claude Code

What's Wrong?

Every conversation creates a new user directory under /sessions/<name>/ inside the VM
and caches all installed plugins there. These directories are never cleaned up after
the conversation ends. Over time, sessiondata.img (fixed at 8.5GB) fills up
internally and all new conversations fail.

Note: this is distinct from #28128 (ENOSPC on temp files within a session). The root
cause here is plugin cache accumulation across sessions, not temp file bloat within a
single session.

What Actually Happens?

After ~80 conversations, every new conversation fails immediately with:
RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create
directory /sessions/<session-name>

coworkd.log on startup shows:
[coworkd] user recovery complete: recovered=81 skipped=8 failed=0

81 old session directories are still present on disk, each containing a full copy of
all installed plugins.

What Should Happen?

Plugin cache directories under /sessions/<name>/mnt/.local-plugins/ and
/sessions/<name>/mnt/.remote-plugins/ should be cleaned up when a conversation ends,
or shared/deduplicated across sessions rather than copied fresh each time.

Error Messages/Logs

RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create directory /sessions/stoic-jolly-fermat

Steps to Reproduce

Install several plugins in Claude Desktop
Have ~80+ conversations over time
Every new conversation fails with the RPC error above
Restarting the app does not help — the image is full

The plugin directories eating the space (per session):
/sessions/<name>/mnt/.skills
/sessions/<name>/mnt/.remote-plugins/
/sessions/<name>/mnt/.local-plugins/cache/
/sessions/<name>/mnt/.local-plugins/marketplaces/

With many plugins installed, each session's cache is substantial. 81 sessions × N
plugins = 8.5GB exhausted.

Impact

Scales inversely with plugin count — power users with many plugins will hit this much
sooner than ~80 sessions. Effectively, the more you use Claude Desktop's plugin
ecosystem, the faster you get bricked.

Workaround

Fully quit Claude Desktop
mv "~/Library/Application

Support/Claude/vm_bundles/claudevm.bundle/sessiondata.img"
~/Desktop/sessiondata.img.bak

Restart Claude Desktop (recreates the image fresh)
Delete .bak to reclaim ~8.5GB

Environment

Claude Desktop version: 1.1.4498
macOS: Darwin 25.3.0
sessiondata.img size at failure: 8.5GB
Sessions accumulated: 81

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude Desktop version: 1.1.4498

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

View original on GitHub ↗

9 Comments

github-actions[bot] · 7 months ago

Found 3 possible duplicate issues:

This issue will be automatically closed as a duplicate in 3 days.

If your issue is a duplicate, please close it and 👍 the existing issue instead
To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

TedWong77 · 7 months ago

doesn't help

msmobileapps · 6 months ago

We hit this exact issue and built a Cowork plugin to help manage it while Anthropic works on a proper fix.

Immediate workarounds:

If sessions still open but Bash fails with ENOSPC:

rm -rf ~/Library/Application\ Support/Claude/vm_bundles/

Then restart Claude — it rebuilds a clean image (~12MB).

If new sessions won't start at all (useradd failed: exit status 12):

mv ~/Library/Application\ Support/Claude/vm_bundles/claudevm.bundle/sessiondata.img \
   ~/Desktop/sessiondata.img.bak

Restart Claude, verify it works, then rm -f ~/Desktop/sessiondata.img.bak to reclaim ~8.5GB.

---

The plugin: We built vm-disk-cleanup — a Cowork plugin that automatically diagnoses which failure mode you're in and gives you the right fix. It covers:

Mid-session ENOSPC (Bash fails but session is open) → guides you through vm_bundles reset
Sessions that won't start at all (useradd failed) → guides you through the sessiondata.img swap
Routine maintenance → cleans .jsonl.bak files, /tmp, npm/pip caches, and large deploy artifacts
Task output file explosion on Mac (separate but related issue) → watchdog hook setup

📦 Now in the Anthropic plugin marketplace: https://github.com/anthropics/claude-plugins-official/issues/1027
🔗 GitHub repo: https://github.com/msmobileapps/vm-disk-cleanup-plugin

Also worth checking out cozempic — it prunes .jsonl session bloat and cleans stale .jsonl.bak files which also contribute to the image filling up.

thebarmask-art · 6 months ago

For anyone still hitting this — I spent weeks documenting this and 50+ other Cowork errors with step-by-step fixes. The sessiondata.img reset takes under 2 minutes and gets you back immediately. Full database at coworkfix.com — free to browse, no signup needed for the basics.

Jae-Park · 6 months ago

Confirmed fix on macOS (M4 MacBook Air) — `rootfs.img` instead of `sessiondata.img`

I experienced the same issue (RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create directory /sessions/<session-name>).

Environment:

macOS (Apple Silicon M4)
Claude Desktop with Cowork
Many MCP plugins installed

Root cause confirmed:
The VM image file was full. However, on my setup the file was named rootfs.img (not sessiondata.img as described in this issue), located at:

~/Library/Application Support/Claude/vm_bundles/claudevm.bundle/rootfs.img

The file had grown to 10GB and was last modified at the exact time the error occurred.

Fix that worked:

mv ~/Library/Application\ Support/Claude/vm_bundles/claudevm.bundle/rootfs.img ~/Desktop/rootfs.img.bak

Then fully quit and restarted Claude Desktop. It automatically recreated a fresh rootfs.img and Cowork worked immediately.

Note for others: If you don't find sessiondata.img, check for rootfs.img in the same bundle directory — this may reflect a version difference in file naming.

msmobileapps · 6 months ago

Hey @Jae-Park — glad you confirmed the fix! 🙌

We actually built a Cowork plugin that automates this exact fix (handles both rootfs.img and sessiondata.img variants):

👉 https://github.com/MSApps-Mobile/claude-plugins/tree/main/plugins/cowork-session-fixer

It detects the stuck session, cleans up the bloated image, and gets Cowork back up — no manual terminal commands needed. Free to install and use.

Hope it helps others hitting this issue!

github-actions[bot] · 4 months ago

Closing for now — inactive for too long. Please open a new issue if this is still relevant.

stavrop · 4 months ago

## Confirmed fix on macOS (M4 MacBook Air) — rootfs.img instead of sessiondata.img I experienced the same issue (RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create directory /sessions/<session-name>). Environment: macOS (Apple Silicon M4) Claude Desktop with Cowork * Many MCP plugins installed Root cause confirmed: The VM image file was full. However, on my setup the file was named rootfs.img (not sessiondata.img as described in this issue), located at: ~/Library/Application Support/Claude/vm_bundles/claudevm.bundle/rootfs.img The file had grown to 10GB and was last modified at the exact time the error occurred. Fix that worked: mv ~/Library/Application\ Support/Claude/vm_bundles/claudevm.bundle/rootfs.img ~/Desktop/rootfs.img.bak Then fully quit and restarted Claude Desktop. It automatically recreated a fresh rootfs.img and Cowork worked immediately. Note for others: If you don't find sessiondata.img, check for rootfs.img in the same bundle directory — this may reflect a version difference in file naming.

I confirm that this worked for me as well (MacOS 26.5)

markmillernz · 3 months ago

## Confirmed fix on macOS (M4 MacBook Air) — rootfs.img instead of sessiondata.img I experienced the same issue (RPC error: ensure user: useradd failed: exit status 12: useradd: cannot create directory /sessions/<session-name>). Environment: macOS (Apple Silicon M4) Claude Desktop with Cowork * Many MCP plugins installed Root cause confirmed: The VM image file was full. However, on my setup the file was named rootfs.img (not sessiondata.img as described in this issue), located at: ~/Library/Application Support/Claude/vm_bundles/claudevm.bundle/rootfs.img The file had grown to 10GB and was last modified at the exact time the error occurred. Fix that worked: mv ~/Library/Application\ Support/Claude/vm_bundles/claudevm.bundle/rootfs.img ~/Desktop/rootfs.img.bak Then fully quit and restarted Claude Desktop. It automatically recreated a fresh rootfs.img and Cowork worked immediately. Note for others: If you don't find sessiondata.img, check for rootfs.img in the same bundle directory — this may reflect a version difference in file naming.

Thank you Jae-Park from Seoul.

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