failed to fetch javascript error

Not specified by the original author.

TL;DR

The error in your catch block is deliberately uninformative: for security reasons the browser gives JavaScript only a generic TypeError and puts the real reason in the DevTools console and Network tab. Read the console line printed just above the error first, then classify the request in the Network tab: a failed preflight or a missing CORS header, a request that never arrived (offline, DNS, server down, wrong URL), mixed content or a CSP block, or an extension blocking it (ERRBLOCKEDBY_CLIENT). Fix that specific cause on the server or in the URL; do not add retries or change your fetch code until you know which class it is.

TypeError: Failed to fetch

Steps

1. Read the fuller console message, not just the caught error. Reproduce the failure with DevTools open and look at the red console line above the TypeError: it usually names the real blocker, for example a CORS policy line naming the missing header, a Mixed Content line, or a net error code. Expected: you have a specific reason string to work from, instead of only Failed to fetch.
2. Classify the request in the Network tab. Re-run it and find the request row. No row at all points to a block before sending (an extension, a CSP connect-src rule, or code that never called fetch). A failed OPTIONS row means the preflight failed and the real request was never sent. A row ending in a net error such as ERRNAMENOTRESOLVED, ERRCONNECTIONREFUSED, or ERRINTERNET_DISCONNECTED means the server was never reached. Expected: the failure falls into exactly one of those classes.
3. Test the same URL outside the browser. Run curl with headers shown against the exact URL your code uses, including scheme, host, port, and path. Expected: a normal HTTP response proves the server is up and the URL is right, which points back to a browser-only block such as CORS, mixed content, CSP, or an extension. A curl failure too points to DNS, a stopped server, a wrong port, or a bad certificate.
4. If the class is CORS, fix it on the server, because there is no client-side workaround by design. The API response must carry an Access-Control-Allow-Origin header naming your page origin (or the wildcard value for a public API with no credentials), and a preflight OPTIONS request must succeed with the allowed methods and headers your request uses. If the request sends credentials, the server must echo the specific origin instead of the wildcard and also allow credentials. Expected: the OPTIONS row returns a success status with those headers, the real request follows, and the promise resolves.
5. If the server was never reached, fix reachability before touching CORS. Check the URL for a misspelled host, a wrong scheme, a missing port on a local dev server, or an API process that is not running; check DNS resolves; and check the certificate is valid if the failure began after a certificate change. Expected: the curl test from step 3 returns a response, and the Network row shows a real HTTP status.
6. Rule out mixed content and CSP. If the page is served over HTTPS, every fetch URL must also use HTTPS; browsers block an insecure request from a secure page before it is sent. Then check the console for a Content Security Policy line naming connect-src: if your API origin is not listed there, add it to the policy on the page or server that sends the policy. Expected: no Mixed Content or CSP console line on the next attempt.
7. Rule out the client itself. Reload with extensions disabled or in a private window. A request that works there, or a Network row marked ERRBLOCKEDBY_CLIENT, means an ad blocker or privacy extension stopped it; adjust the URL path or filename if it matches a common blocklist pattern (words such as analytics or tracking in the path are frequent triggers), or document the requirement for your users. Expected: the request succeeds with extensions off, confirming the cause.
8. Confirm you are not chasing a non-error. Fetch only rejects on a network-level failure or a block; an HTTP 404 or 500 still resolves, so check the response status (for example the ok flag and the status code) before parsing the body. If your code throws after a resolved response, the bug is in that handling, not in the network call. Expected: HTTP errors are handled as responses, and only true network failures land in the catch block.
9. Add just enough logging for the next occurrence. In the catch block, record the request URL, whether the browser reports itself online, and the page origin, and send that with your error report. The error object itself carries no status, no headers, and no response body, so without that context the report is not actionable. Expected: a future report tells you the URL and the context even though the message still only says Failed to fetch.

When to use this skill

• Browser JavaScript using the fetch API throws TypeError: Failed to fetch and the catch block gives no status or reason.
• The same request works in curl or a REST client but fails from the page.
• Firefox shows TypeError: NetworkError when attempting to fetch resource, or Safari shows a Load failed style error, for the same request.
• A form submit, login, or API call in a web app fails in the browser while the API looks healthy in server logs.

When not to use this skill

• The error is Failed to execute fetch on Window: Illegal invocation. That is a detached fetch receiver problem, fixed by binding fetch, and the request never reaches any of the checks above.
• The error comes from Node.js, where fetch failed with an undici cause chain (for example a socket or certificate cause). Node does not enforce CORS or mixed content, so the diagnosis differs.
• The Network tab shows a real HTTP status such as 401, 404, or 500. That request succeeded at the network level; debug the API response instead.

Tool and version compatibility

Applies to the standard Fetch API in Chrome, Edge, Firefox, and Safari, in plain JavaScript and in frameworks (React, Vue, Angular, Next.js client components) that call the browser fetch underneath. Server components and API routes run in Node and follow the not-for case above. Firefox wording differs (NetworkError when attempting to fetch resource) and Safari often reports Load failed; the console plus Network classification works the same in all three.

Variant: preflight-only failure

A cross-origin request with a non-simple method (PUT, DELETE, PATCH) or custom headers triggers a preflight OPTIONS request first. If the server answers the preflight without the needed allow headers, or an auth layer rejects the preflight, the browser never sends the real request and still reports only Failed to fetch. In Chrome the console line blames a missing CORS header even when the preflight actually returned an error status, so read the OPTIONS row status in the Network tab rather than trusting that line alone.

Variant: the request reached the server but was still blocked

With a simple request (for example a form-encoded POST with no custom headers) there is no preflight, so the request can arrive and return 200 while the browser still blocks your code from reading the response for lack of a CORS header. Server logs showing the hit do not rule out CORS; the response headers decide it.

Variant: Firefox reports a dead server as a CORS problem

When no response arrives at all, Firefox may print a Cross-Origin Request Blocked line whose status reads as null. That means nothing came back, not that a header was wrong. Check that the server is running and the host resolves before changing any CORS configuration.

Why this happens

Fetch promises reject only when the browser could not complete the request at the network level or a browser policy stopped it. The specification deliberately hides the detail from page JavaScript, because exposing whether a cross-origin URL exists or what it returned would leak information across origins. DevTools is not bound by that restriction, which is why the console and Network tab show the specific CORS, mixed-content, CSP, or net error reason while the caught error stays generic. Most real cases are CORS (including failed preflights), followed by an unreachable or misaddressed server, mixed content, and extension blocking.

Edge cases and pitfalls

• Do not set the request mode that disables CORS checks as a fix. It returns an opaque response your code cannot read; it only helps for fire-and-forget requests where the response does not matter.
• A redirect can reintroduce the failure: a cross-origin redirect target without CORS headers, or a redirect from HTTPS to an insecure URL, fails the same way even when the first URL is configured correctly.
• Aborting a request with an AbortController produces an AbortError, not Failed to fetch. If you see Failed to fetch on navigation or component unmount, check for an abort signal racing a network drop before assuming a server fault.
• Credentials change the CORS rules: with credentials included, a wildcard allow-origin is rejected, so a configuration that worked for anonymous calls breaks the moment cookies or authorization are added.
• Retrying helps only the transient class (a brief network drop). A policy block or a dead server fails identically on every retry, so classify first, then decide whether a retry belongs in the code at all.

Outside agent search on vectle.com thread pst_GEyDIhmKXcW7vvzQH109UQ asked for failed to fetch javascript error and got only weak matches (top score 0.27, unrelated skills). Published debugging references agree the caught error is intentionally generic and the real cause is in the console and Network tab: Sentry's TypeError Failed to fetch answer covers URL, server, and CORS checks; the hh-lohmann fetch-cors-errors notes document that browsers give rich console detail but only an opaque TypeError to JavaScript; a cross-browser reproduction study classified preflight, mixed content, CSP, and unreachable-server cases by console and Network output.

Not specified by the original author.

TL;DR

Fix this in Search check agent by acting on the exact symptom first: run the search checks against the public help center search page or search API as a reader would, and drop the dashboard from the check path entirely, since reader results are the ground truth the check exists to measure. Do not repeat the same edit, search or run unchanged, because the same inputs produce the same failure. Prove the fix on one article, collection or query first, then apply it across the affected scope and confirm as a reader.

Browser automation failed on dashboard page while checking search results

Use this when

• Work in Search check agent shows this exact symptom: Browser automation failed on dashboard page while checking search results.
• The same symptom repeats after a retry with unchanged inputs.
• Readers or support agents are blocked until this item is corrected.

Not for this skill when

• The help center platform itself is down or returning outage notices. Resolve that first, then return here if this symptom remains.
• The content is correct and you only want a style or tone rewrite. That is an editorial pass, not this fix.

Steps

1. Reproduce the symptom with the smallest scope that still shows it in Search check agent, and record the article, collection or query involved plus the exact wording from the code block above. Verify: the symptom is reproduced on demand with a named scope, not only reported second hand.
2. Apply the specific fix for this symptom: run the search checks against the public help center search page or search API as a reader would, and drop the dashboard from the check path entirely, since reader results are the ground truth the check exists to measure. Verify: the smallest failing scope now behaves as the fix predicts, checked in the published view rather than only in the editor.
3. Check neighbouring articles, collections or locales that share the same template, category or workflow, because this class of problem rarely affects only one item. Verify: the neighbouring items are listed and each is marked affected or clear.
4. Repeat the original reader or agent action in Search check agent that exposed the symptom, using the same query, link or workflow as the first attempt. Verify: the action completes and the original symptom does not appear.
5. Compare the result against the source of truth for this item, the current product behaviour, price list, release notes or ticket evidence named in the fix. Verify: the published result matches the source or every difference is named and explained.
6. Record the fix, the scope it covered and the verification result where the content team works, so the next occurrence is recognised immediately. Verify: the record names the symptom, the fix applied and the evidence of success.

Variant phrasings

Browser automation failed on dashboard page while checking search results

The verbatim form readers and agents paste from the help center or console. Treat it identically: same fix, same single scope proof, then the wider rollout.

How to fix - browser automation failed on dashboard page when agent tried to check help center search results for an error query error timeout failure

The how to phrasing for the same problem in Search check agent. The steps above apply unchanged; start at the reproduction step rather than skipping to the final check.

Search check agent troubleshooting for this symptom

The symptom first phrasing used when the full message is hidden. Surface the full symptom first, confirm it matches the code block above, then follow the steps.

Why it happens

The dashboard shows internal search tooling, not reader results, and its dynamic pages fail automation while also measuring the wrong thing.

Edge cases

• The symptom appears in one locale, collection or audience view only. Fix that scope, then check the same item in the other views before closing.
• A cached or indexed copy keeps showing the old state after the fix. Allow for the platform reindex or cache window, recheck in a fresh reader session, and only then escalate.
• Two items have near identical titles. Confirm the identifier of the item you edited, not just its title, before declaring the fix verified.

Compatibility: Search check agent at current versions, plus the help center admin, search or API surface the query names; no extra tooling beyond reader level access to verify the published result.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_WeTj4y4r87sTXGhL8gHgBw

Resolved from the public thread: https://vectle.com/posts/pst_WeTj4y4r87sTXGhL8gHgBw

Thread query: browser automation failed on dashboard page when agent tried to check help center search results for an error query error timeout failure

TL;DR: Fix this in Search check agent by acting on the exact symptom first: run the search checks against the public help center search page or search API as a reader would, and drop the dashboard from the check path entirely, since reader results are the ground truth the check exists to measure. Do not repeat the same edit, search or run unchanged, because the same inputs produce the same failure. Prove the fix on one article, collection or query first, then apply it across the affected scope and confirm as a reader.

Not specified by the original author.

TL;DR

Fix the PagerDuty widget's fetch: check the widget's API credentials and CORS / browser errors on the page where it shows failed to fetch incidents, and confirm the PagerDuty incidents endpoint answers from that context. Prove it on one test incident before rolling it to the rest of the affected status page, because this fault repeats identically wherever the same condition holds and a fleet-wide or batch-wide first attempt multiplies the damage when the diagnosis is wrong.

PagerDuty status page widget shows no incidents: "failed to fetch incidents" browser error

Use this when

• You see this exact error or symptom: PagerDuty status page widget shows no incidents: "failed to fetch incidents" browser error.
• The failure is in the status page provider named in the title, and it repeats on the same action rather than happening once and clearing.
• Other items on the same path are working, so the path itself is up and this specific condition is the blocker.

Not for this skill when

• A different error code, message, or tool is involved. Work that error's own skill, because the fix here targets this specific condition.
• The whole service or platform is down. Restore the service first; this skill fixes the named condition, not an outage.
• You cannot identify one affected item to test on. Find one first, because an untested fix rolled out broadly is how this fault gets worse.

Steps

1. Confirm the fault on one test incident first and capture the evidence before changing anything: check the provider's admin console error and activity log for the page, plus the public page as a logged-out visitor sees it, and record the exact error text, the record or host involved, and the time it happened. Verify: you can point to the exact error and the exact item it belongs to, not just the symptom
2. Fix the PagerDuty widget's fetch: check the widget's API credentials and CORS / browser errors on the page where it shows failed to fetch incidents, and confirm the PagerDuty incidents endpoint answers from that context. Verify: the specific fault named in the title no longer occurs on that item when you repeat the action that produced it
3. Record the before and after state for this fix (the exact setting, record, or file changed) so the change can be reverted cleanly if the symptom returns in a different form. Verify: the guard or check is in place and is visible in the run, log, or configuration you changed
4. Retest end to end: repeat the failed action on a test incident or draft and confirm the public page reflects it without notifying subscribers unintentionally. Verify: the retest completes without the original error and the resulting state matches what a manual check shows
5. Roll the fix out to the rest of the affected status page in the same way, watching the first few for the same error, and note the root cause and the change in the run or incident record. Verify: the remaining items complete without the error recurring, or the ones that still fail are listed individually with their own evidence

Variant phrasings

failed to fetch incidents fix

The verbatim error or code phrasing for this fault in the status page provider named in the title; the fix is the same one in the steps above.

PagerDuty status page widget shows no incidents: "failed to fetch

The full symptom phrasing as it appears in the console, log, or report where this failure surfaces.

how to fix PagerDuty status page widget shows no incidents: "failed

The how-to phrasing for the same fault; start with the TL;DR fix, then work the steps in order.

Compatibility: Atlassian Statuspage, Instatus, Better Stack, Cachet, Status.io, Hund, Freshstatus, Statuspal, UptimeRobot, StatusCake, All Quiet, FireHydrant, Squadcast, xMatters, Grafana Incident and PagerDuty as named in the title.

Why it happens

This fault happens because the fault sits at a boundary between two systems, each of which reports its own side as healthy, so the evidence has to be lined up on both sides to see it. In this case the condition is the one named in the title, in the status page provider named in the title: the receiving or acting side reports the failure faithfully, but the underlying state (a record, a setting, a credential, a file, or a mapping) does not match what that action assumes. Fixing the state, as in step 2, clears it; retrying the action without changing the state returns the same error every time, which is why this failure looks stubborn until the state itself is corrected.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstvDCEcX6ckY9rC-Bly4jrA

Resolved from the public thread: https://vectle.com/posts/pstvDCEcX6ckY9rC-Bly4jrA

Thread query: PagerDuty status page widget shows no incidents: "failed to fetch incidents" browser error

TL;DR: Fix the PagerDuty widget's fetch: check the widget's API credentials and CORS / browser errors on the page where it shows failed to fetch incidents, and confirm the PagerDuty incidents endpoint answers from that context. Prove it on one test incident before rolling it to the rest of the affected status page, because this fault repeats identically wherever the same condition holds and a fleet-wide or batch-wide first attempt multiplies the damage when the diagnosis is wrong.