TL;DR
Users reported that updating Claude Code to 2.1.0 produces an "Invalid Version: 2.1.0 (2026-01-07)" error and the CLI fails to start. Comments point to semver parsing of a date suffix in the tool's own version string; several user workarounds were shared and a collaborator indicated a fix was deployed.
What happened
On January 7, 2026 a public issue was opened against the anthropics/claude-code repository reporting that Claude Code 2.1.0 fails to run after update, producing an "Invalid Version: 2.1.0 (2026-01-07)" error at startup. Multiple contributors replicated the failure, primarily on macOS, and supplied stack traces showing a semver parser error. Community troubleshooting identified the culprit as the version string containing a date suffix; commenters recommended coercing or stripping the date before parsing. Users posted several local workarounds, such as clearing or locking a cached changelog file (~/.claude/cache/changelog.md), editing the cachedChangelog or lastReleaseNotesSeen entries in ~/.claude.json, or reverting to the prior native installer version (2.0.76). A repository collaborator later marked the problem fixed and closed the report as a duplicate of a related issue, and some users said restarting picked up the remedy.
Why it matters
- CLI users may be unable to run or reinstall the tool after updating, disrupting developer workflows.
- A malformed version string can break automated parsing and sorting logic in client tooling.
- Workarounds require editing or locking local cache files, which may be error-prone for nontechnical users.
Key facts
- Error reported: "Invalid Version: 2.1.0 (2026-01-07)" observed at CLI startup.
- Issue filed as GitHub issue #16673 against anthropics/claude-code on 2026-01-07.
- Comments and stack traces indicate the semver parser fails on the date suffix in the version string.
- Affected platform called out in the thread: macOS (users also reported Node versions and terminals).
- Workarounds reported: emptying ~/.claude/cache/changelog.md and setting restrictive permissions, editing ~/.claude.json to remove or alter cachedChangelog/lastReleaseNotesSeen, or using an older native installer (2.0.76).
- A collaborator commented the problem was fixed and the issue was closed as a duplicate of a related report.
- GitHub Actions bot and other participants linked multiple duplicate issues and alerts in the discussion.
What to watch next
- Monitor the anthropics/claude-code repository for an official release note or merged fix (users reported a collaborator comment saying "Fixed! Restart to update").
- If you encounter the error, check and edit ~/.claude.json and ~/.claude/cache/changelog.md as community workarounds suggest.
- not confirmed in the source
Quick glossary
- semver: Semantic Versioning, a versioning scheme using MAJOR.MINOR.PATCH to convey backward-compatible changes, features, and fixes.
- CLI: Command-line interface, a tool that is operated through text commands in a terminal.
- changelog: A file or record that lists notable changes, fixes, and updates made across releases of software.
- stack trace: A report of active stack frames at a point in time during program execution, commonly used for debugging errors.
Reader FAQ
What error do users see when the bug occurs?
They report an "Invalid Version: 2.1.0 (2026-01-07)" error at CLI startup.
What causes the error?
Comments point to the semver parser choking on a date suffix in the tool's version string.
Are there fixes or workarounds?
Community-suggested workarounds include emptying or locking ~/.claude/cache/changelog.md, editing cachedChangelog or lastReleaseNotesSeen in ~/.claude.json, or reverting to the older native installer; a repository collaborator also commented that the issue was fixed and recommended restarting to update.
Is this a regression from a previously working version?
The original reporter wrote that this "never worked" for them; broader regression status is not confirmed in the source.
anthropics / claude-code Public Notifications Fork 3.8k Star 52.6k Code Issues 5k+ Pull requests 94 Actions Security 13 [BUG] Invalid Version: 2.1.0 (2026-01-07) #16673 New issue Closed as duplicate of #16682…
Sources
- Claude Code CLI Broken
- [BUG] Force quitting Claude Code during auto-update …
- Troubleshooting – Claude Code Docs
- Claude Code Troubleshooting Guide: Fix Common Issues
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