Grammarly throwing an authentication error, refusing to load suggestions, or timing out mid-document? You are not alone — most Grammarly errors trace back to a handful of causes across the browser extension, desktop app, and API, and each has a specific fix. Below are 7 that actually work.
1. Sign Out Completely and Back In
A stale authentication token is the most common trigger for a plain auth failure. Sign out from the extension or app, close it entirely, and sign back in — this resolves the majority of login-related errors in under a minute.
2. Disable Other Browser Extensions
Ad blockers, other writing tools, and some privacy extensions commonly conflict with Grammarly’s browser extension, especially when both try to inject into the same text field. Open an incognito window, where extensions are disabled by default, and test there. If it works, re-enable your other extensions one at a time to find the conflict.
3. Wait Out a Rate Limit (HTTP 429)
If you are integrating Grammarly through its API and seeing repeated failures, check for a 429 status code, which indicates you have hit a rate limit rather than encountering a real outage. Implement exponential backoff in your requests, or simply space out your calls, rather than retrying immediately.
4. Delete the Local Configuration Folder (Desktop App)
A corrupted local config file is a common cause of the desktop app failing to start or sync properly. Close Grammarly, delete the folder at %AppData%\Grammarly on Windows or ~/Library/Application Support/Grammarly on macOS, then reopen the app — it will rebuild a fresh configuration automatically.
5. Disable Your VPN
VPNs and some corporate proxies interfere with Grammarly’s connection in ways that produce generic network errors rather than a clear message about the actual cause. Turn off your VPN, reload, and test again before assuming the service itself is down.
6. Ask IT to Whitelist Grammarly’s Domains
On a corporate or school network, Grammarly may be partially blocked by a firewall or content filter without any obvious error. Ask your network administrator to whitelist grammarly.com and its subdomains so all required resources can load without interception.
7. Test in a Different Document or Browser
If the error only happens in one specific document, an unusual formatting element or a very long document can be the actual cause rather than Grammarly itself. Try a short, plain-text document, and separately try a different browser, to isolate whether the problem is document-specific or account-wide.
Signing out and back in, or testing in incognito mode, resolves most Grammarly errors on their own. If you are still stuck after all seven steps and need a working alternative in the meantime, ProWritingAid covers similar grammar and style checking without depending on the same backend.
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