Can't Reach Claude Error: Every Fix That Actually Works

The can't reach Claude error means your app, browser, or terminal could not open a connection to Anthropic's API — it's a network-path problem, not an account problem. Check status.claude.com first: if Anthropic is down, wait it out; if it's green, the fix is on your side — VPN, proxy, DNS, cache, or a stopped Windows service.

What the can't reach Claude error actually means

Claude shows some version of this message when the app in front of you — a browser tab, the desktop app, or a terminal running Claude Code — cannot complete a request to Anthropic's API servers. The wording shifts by surface: claude.ai says "Can't reach Claude", Claude Code prints a Claude API connection error, and Claude Cowork on Windows reports "Can't reach the Claude API from Claude's workspace". Different clothes, same body: the can't reach Claude error means your request never made a successful round trip to Anthropic's servers.

That tells you something useful immediately. This is a connectivity failure, not a judgment about you. Your account isn't suspended, your subscription hasn't lapsed, and your conversation history is intact. Somewhere between your machine and Anthropic's servers — browser cache, VPN tunnel, corporate proxy, DNS resolver, a stopped Windows service, or Anthropic's own infrastructure — one link is broken. Troubleshooting is just finding which link, and we've hit every variant of this while running Claude across web, desktop, and CLI daily.

The 60-second triage: do this before touching anything

Our strong opinion after two years of hitting the can't reach Claude error at the worst possible moments: people waste twenty minutes clearing caches when sixty seconds of diagnosis would have told them the problem was never on their machine. Run these four checks in order — each halves the remaining possibilities.

If step 1 shows an incident, everything below is irrelevant — bookmark the page, subscribe to updates, and check back in twenty minutes. Anthropic had several publicly acknowledged incidents in the first half of 2026, including outages in March and June, so "it's them, not you" is a genuinely common outcome.

Fixes by platform: claude.ai, Desktop, Claude Code, and Cowork

Once triage points at your side, the fastest fix depends on where the can't reach Claude error appeared. This is the table we wish someone had handed us the first time:

claude.ai in the browser

Nine times out of ten, Claude not working in the browser comes down to stale state or an interfering extension. Hard-refresh first. If an incognito window works while your normal window doesn't, the diagnosis is done: clear site data for claude.ai (cache and cookies — you'll need to log back in) or disable extensions one by one, starting with ad blockers and privacy shields, which love to eat the streaming connections Claude uses to deliver responses.

Claude Code in the terminal

Claude Code talks to the same Anthropic API but adds failure points of its own. Work through these in order:

1. Run claude doctor (or /doctor inside a session). It checks your installation, version, and connectivity in one shot and names the problem more often than not.
2. Check ANTHROPIC_API_KEY. A stale or invalid key in your environment overrides your subscription login and produces connection-flavored errors that look like network failures. echo $env:ANTHROPIC_API_KEY on Windows, echo $ANTHROPIC_API_KEY elsewhere — if you see an old key, unset it.
3. Check proxy variables. If your shell exports HTTPS_PROXY or HTTP_PROXY pointing at a dead or corporate proxy, every request routes through it. Unset them and retry.
4. Ask about the firewall. Corporate networks that allow claude.ai often still block api.anthropic.com or downloads.claude.ai — the latter is why updates silently fail. Have IT allowlist all three domains.

Claude Cowork on Windows: the workspace variant

The message "Can't reach the Claude API from Claude's workspace" is a different beast, and it confused us for a full afternoon the first time. Claude Cowork runs its tasks inside a Hyper-V sandbox on Windows, managed by a service called CoworkVMService — and that service has a documented habit (GitHub issue #26257) of stopping after a reboot or a sleep/wake cycle. Claude itself is fine; the sandbox just lost its network.

The fix takes ninety seconds:

1. Quit Claude completely — right-click the system tray icon and exit, don't just close the window.
2. Open PowerShell as Administrator and run Start-Service CoworkVMService.
3. Relaunch Claude and rerun your Cowork task.

If the service refuses to start, disable your VPN before anything else — VPN NAT routing conflicts with the Hyper-V virtual network and will keep knocking the sandbox offline no matter how many times you restart the service.

Network causes: VPN, corporate proxy, and DNS

When every Claude surface fails on one network but works on another, the network itself is guilty. Three suspects, in order of arrest frequency:

VPNs. The single most common local cause, full stop — Anthropic's own help documentation recommends disabling your VPN as an early step. Shared exit nodes get flagged for abuse, and the extra routing hop times out streaming responses. Disable it, retry, and if that fixes it, try a different server region before giving up on the VPN entirely.

Corporate proxies and firewalls. TLS inspection middleboxes break the long-lived streaming connections Claude depends on, even when they technically allow the domain. The tell: everything fails at the office and works from home. The fix is a one-time IT request to allowlist claude.ai, api.anthropic.com, and downloads.claude.ai without inspection.

DNS. If your resolver can't find Anthropic's servers, nothing upstream matters. Flush first — ipconfig /flushdns on Windows — then switch your resolver to Cloudflare (1.1.1.1) or Google (8.8.8.8). We've watched a flaky ISP resolver produce intermittent Claude API connection errors for days while every other site loaded fine, which is exactly what makes DNS problems so maddening to spot.

Anthropic's outage or your problem? How to tell in one glance

The single most useful skill here is knowing whose problem the can't reach Claude error is, because the two failure modes need opposite responses: theirs needs patience, yours needs action.

One asymmetry worth internalizing: Anthropic-side problems resolve themselves, usually within the hour, and no amount of cache-clearing accelerates them. Your-side problems never resolve themselves. So the status page isn't just step one — it decides whether steps two through ten should exist at all. And if Claude is down mid-deadline, having a second assistant ready is legitimate insurance; our Claude vs ChatGPT comparison covers what that fallback trades away.

How we stopped losing time to this error

Prevention beats diagnosis, and four cheap habits eliminated most of our downtime:

1. Subscribe to status.claude.com. Email or RSS. Thirty seconds of setup means you find out it's Anthropic before you've touched a single setting.
2. Keep a second surface installed. When Claude Desktop misbehaves, claude.ai in a browser confirms in ten seconds whether the problem is the app or the connection — and usually lets you keep working either way.
3. Get the allowlist done once. If you're on a corporate network, file the IT ticket for all three domains now, not during an outage-shaped emergency.
4. Pin reliable DNS. Setting 1.1.1.1 at the router level removed our intermittent failures entirely — the flakiest component in the chain turned out to be the ISP's resolver, not anything Anthropic ships.

For Claude Code specifically, claude doctor deserves a deeper walkthrough than we can give it here — we're planning a dedicated guide to Claude Code diagnostics and health checks. And if repeated capacity messages are your real complaint, that's a usage-limits question rather than a connectivity one; hold that thought for our upcoming piece on Claude's usage limits and plan tiers.

Claude pricing at a glance

For the full breakdown of every plan, see our how much Claude costs guide.