Click here to open the tool in a new window →deadlink-viewer（YouTube Tutorial Video）
Each unit may import the CSV file as indicated in the tool. Related files (please log in with your school Outlook account)：
| Error Code | Description | Suggested Action |
|---|---|---|
| 404 | (Client Request Error) The target page does not exist; it may have been removed, moved, or the URL was entered incorrectly. | Update or remove the link |
| 403 | (Client Request Error) The server refused access; may be due to access control or the scanning tool being identified as a crawler. | Verify manually; if the page loads normally in a browser, ignore. |
| 400 | (Client Request Error) Malformed request; commonly caused by mixing HTTP/HTTPS or a syntax error in the URL. | Manually correct the URL syntax and verify again. |
| -1 Timeout | The scanning tool timed out waiting for a connection; the remote server responded too slowly. | Can be ignored. |
| redirect | (Abnormal Redirect) Redirect loop; the browser cannot reach the final destination. | Update to the final target URL. |
| 401 | (Client Request Error) Login required to access; no valid credentials were provided. | Confirm whether the page should be publicly accessible. |
| 402 | (Client Request Error) Reserved status code; rarely used in practice. | Verify manually. |
| 405 | (Client Request Error) The remote server does not allow this request method. | Verify manually; this is usually a configuration issue on the remote server. |
| 410 | (Client Request Error) The page has been permanently removed; more definitive than 404 in that it will not be restored. | Remove the link directly. |
| 429 | (Client Request Error) Too many requests in a short period; rate-limited by the remote server. | Can be ignored. |
| 500 | (Server-Side Error) Internal server error on the remote end; unrelated to the client request. | If the error persists, consider replacing or removing the link. |
| 503 | (Server-Side Error) Server temporarily unavailable; usually under maintenance or overloaded. | Can be ignored. |
| 504 | (Server-Side Error) Backend server response timed out; the page exists but cannot be loaded temporarily. | Can be ignored. |
| 999 | The platform actively blocks automated crawlers; commonly seen on social platforms such as LinkedIn. | Verify manually; if the page loads normally in a browser, ignore. |
| cf-1001 | Cloudflare DNS resolution failure; the domain may be disabled or misconfigured. | Verify manually; if inaccessible, remove the link. |
| -1 Not Found | DNS cannot resolve the domain; the domain has expired or never existed. | Remove the link directly. |
| -1 Invalid URL | Malformed URL; for example, missing https://, containing unencoded Chinese characters, or extra spaces. | Correct the URL syntax and verify again. |
Reference: https://kucw.io/blog/http-status-code/
For any questions or suggestions regarding usage, please feel free to contact us by email or phone. Thank you.