Failed to fetch что значит
Ошибка Error 503 Backend fetch failed что делать
Компьютер нужен нам в первую очередь для выхода в Интернет, где на каждом шагу подстерегает большое количество опасностей. Сегодня я поделюсь информацией об одной из таких угроз – ошибке Error 503 Backend fetch failed, и расскажу, что нужно делать, чтобы от нее избавиться. Неприятно то, что данная проблема может возникнуть абсолютно на любом устройстве, использующемся для выхода в Сеть, включая и мобильные гаджеты. Но, как всегда, раз есть ошибка, то есть и решения, созданные умными головами, которыми мы и воспользуемся.
Чтобы подобрать верное решение, необходимо сначала понять причины, из-за которых вылетает ошибка Error 503.
Причины появления проблемы
Данный код ошибки означает, что сервер по каким-то внутренним причинам не в состоянии ответить на обращенный к нему запрос. Чаще всего это связано с:
Как видим, ошибка вылетает из-за сбоев в техническом состоянии удаленного сервера по не зависящим от пользователя обстоятельствам.
Способы решения ошибки Error 503 Backend fetch failed
Понятно, что от обычного пользователя, сидящего за экраном своего компьютера или держащего в руках мобильный гаджет, почти ничего не зависит – он не сможет при помощи своих средств решить техническую сторону ошибки. Тем не менее стоит предпринять несколько шагов, с помощью которых иногда можно сразу разрешить проблему.
Не забывайте перезагружать компьютер после каждых внесенных в него изменений. Это позволит корректно установить все обновления.
Error 503 Backend fetch failed исправляем за минуту
При работе в сети Интернет, мы можем столкнутся с проблемой обработки страницы серверов и увидеть на экране ошибку Error 503 Backend fetch failed. Особо критического в ней ничего нет, но давайте попробуем разобраться в причинах возникновения и решить данную неисправность.
Как Вы можете знать, все веб-сервера работают на двух базовых серверных утилитах — Apache и Nginx. При неверной настройке сервера может возникнуть проблема с отрисовкой бекэнд части, отвечающей за скрипты.
При работе сайта к примеру на CMS WordPress или Magento, в Apache нужна дополнительная настройка и включение служб для его корректной работы.
Причины возникновения проблемы
Как можно видеть, все основные проблемы связаны серверной частью. Вам следует внимательно отнестись к настройках или сбросить их по умолчанию. Файлы конфигурации для обоих типов конфигураций, можно найти в интернете или запросить у хостинг-провайдера.
Решение ошибки Error 503 Backend fetch failed
Для каждой причины есть свойственное простое решение. Если вы обычный пользователь который столкнулся с ошибкой Error 503 Backend fetch failed при заходе на сайт, то попробуйте зайти на него через некоторое время, пока администратор исправит ситуацию. Для владельцев ресурсов, мы составили свои рекомендации по исправлению.
Как можно убедится, что проблема не возникает сама по себе. В частности все заключается в правильной настройке и поддержке сервера. Обратитесь к специалистам или оставьте комментарий под этой записью, мы попробуем помочь вам.
How to fix ‘TypeError: Failed to fetch’?
I’m getting a TypeError: Failed to fetch error when I attempt to send a post request using fetch on the front-end and an express route on the back-end.
I’m able to successfully create the new user in the db, but when attempting to obtain that new user data through the fetch promise, that’s when the error is being thrown.
app.js
users.js
server.js
I need to get that user object back in order to access its data.
Edit: So, I’ve figured out that the issue has to do with how the request is submitted on the front-end. If I create the following function and then call it when app.js is loaded, then everything works:
But, if I try to call this function either through onsubmit in the form or onclick on the button in the html, or if I use an event listener (see below, which is in app.js ), then I get the TypeError: Failed to fetch error:
This is even more baffling to me. I’m required to use Vanilla JS and I need to create the user through a form submission, but not sure what I need to adjust here.
Solution Foiled by the event.preventDefault() again. This was all I needed.
3 Answers 3
The issue was that the page was reloading, which kept me from getting the data back in time. The solution was to simply add event.preventDefault() inside the listener.
app.js
The question is about «TypeError failed to fetch». The wording of the message sends one in the direction of network/server/CORS type issues as explored in other answers, but there is one cause I have discovered that is completely different.
I had this problem and took it at face value for some time, especially puzzled because it was provoked by my page POSTing in Chrome but not in Firefox.
It was only after I discovered chrome://net-internals/#events and saw that my request suffered from ‘delegate_blocked_by = «Opening Files»‘ that I finally had a clue.
My request was POSTing a file uploaded from the user’s computer via a file input element. This file happened to be a file open in Excel. Although it POSTed fine from Firefox, it was only when closed that it could be posted in Chrome.
Users of your web application need to be advised about this potential issue, and web developers should also be aware that «TypeError failed to fetch» can sometimes mean «TypeError didn’t get as far as trying to fetch»
Getting «TypeError: failed to fetch» when the request hasn’t actually failed
I’m getting a valid response:
But also getting this error at the same time:
When I remove credentials: «include», it works on localhost, but not on the server.
I tried every solution given on StackOverflow and GitHub, but it’s just not working out for me.
9 Answers 9
The issue could be with the response you are receiving from back-end. If it was working fine on the server then the problem could be with the response headers. Check the Access-Control-Allow-Origin (ACAO) in the response headers. Usually react’s fetch API will throw fail to fetch even after receiving response when the response headers’ ACAO and the origin of request won’t match.
I understand this question might have a React-specific cause, but it shows up first in search results for «Typeerror: Failed to fetch» and I wanted to lay out all possible causes here.
The Fetch spec lists times when you throw a TypeError from the Fetch API: https://fetch.spec.whatwg.org/#fetch-api
Relevant passages as of January 2021 are below. These are excerpts from the text.
4.6 HTTP-network fetch
To perform an HTTP-network fetch using request with an optional credentials flag, run these steps:
.
16. Run these steps in parallel:
.
2. If aborted, then:
.
3. Otherwise, if stream is readable, error stream with a TypeError.
To append a name/value name/value pair to a Headers object (headers), run these steps:
Filling Headers object headers with a given object object:
To fill a Headers object headers with a given object object, run these steps:
Method steps sometimes throw TypeError:
The delete(name) method steps are:
The set(name, value) method steps are:
To extract a body and a Content-Type value from object, with an optional boolean keepalive (default false), run these steps:
.
5. Switch on object:
.
ReadableStream
If keepalive is true, then throw a TypeError.
If object is disturbed or locked, then throw a TypeError.
In the section «Body mixin» if you are using FormData there are several ways to throw a TypeError. I haven’t listed them here because it would make this answer very long. Relevant passages: https://fetch.spec.whatwg.org/#body-mixin
In the section «Request Class» the new Request(input, init) constructor is a minefield of potential TypeErrors:
In the Response class:
The new Response(body, init) constructor steps are:
.
2. If init[«statusText»] does not match the reason-phrase token production, then throw a TypeError.
.
8. If body is non-null, then:
1. If init[«status»] is a null body status, then throw a TypeError.
.
The static redirect(url, status) method steps are:
.
2. If parsedURL is failure, then throw a TypeError.
In section «The Fetch method»
The fetch(input, init) method steps are:
.
9. Run the following in parallel:
To process response for response, run these substeps:
.
3. If response is a network error, then reject p with a TypeError and terminate these substeps.
In addition to these potential problems, there are some browser-specific behaviors which can throw a TypeError. For instance, if you set keepalive to true and have a payload > 64 KB you’ll get a TypeError on Chrome, but the same request can work in Firefox. These behaviors aren’t documented in the spec, but you can find information about them by Googling for limitations for each option you’re setting in fetch.
File Save Error: Failed to fetch #3964
Comments
leonsp commented Feb 22, 2018
Data scientists on my team are regularly seeing one of these two messages in JupyterLab:
Is there something we can do to prevent or debug this?
Reloading the page in the browser tends to resolve the issue, but this is not user-friendly. It might have something to do with the number of tabs open in JupyterLab.
This has a different error message from #3506
The text was updated successfully, but these errors were encountered:
blink1073 commented Feb 22, 2018
Hi @leonsp, those messages mean that the server is giving 400 errors when trying to update the file browser listing or saving the file. Does this only happen sporadically?
leonsp commented Feb 23, 2018
@blink1073 It happens as soon as we have more than
6 notebooks open in JupyterLab at the same time.
blink1073 commented Feb 26, 2018
Does it happen repeatedly when you are in that state or does it go away after you dismiss one or two dialogs?
mewwts commented Mar 7, 2018
kuchaale commented Mar 16, 2018 •
95 MB) since it is full of pdfs. It did not happen before when I displayed my outputs in pngs ( set_matplotlib_formats(‘png’, ‘pdf’) ).
I use jupyterlab of version 0.31.8.
jasongrout commented Mar 16, 2018
It seems like I see error messages too when I have big (several hundred mb) csv files open, particularly in the autosave intervals, I think. I haven’t tracked it down yet.
thongnnguyen commented Apr 4, 2018
I’m using juyterlab 0.31.12 under conda 4.5.0, jupyternotebook 5.4.1 (Py3.6)
DavidPowell commented Sep 23, 2018
I am noticing similar problems. They only seem to happen when I am accessing the notebook server remotely, rather than via localhost. However, I definitely have a good connection to the machine in question, as I have a windows remote desktop connection running fine.
seriousran commented May 8, 2019
I have the same issue but in a different situation.
Other files are available to save. But the only one file is still failed to fetch. There is no problem to edit the file through terminal. The problem occurs only through jupyterlab file editor.
stefansedich commented May 17, 2019 •
We are also experiencing the same, occasional errors saving a notebook, that oddly can be saved with the removal of particular cells.
Looks like clearing the browser cash fixed the random issues up for one user.
zbarry commented May 27, 2019
I am experiencing this issue, but only when I am accessing the Lab server remotely over a VPN. Remote from inside the network (i.e., laptop to workstation over wireless) is fine. Restarting the jupyterlab server (0.35.5) worked for a bit, but after a while, the same error popped up, and I was no longer able to save notebooks.
Also, no dice on the browser cache clear. Happens on both Chrome (74.0.3729.169) and Firefox (67.0)
NCTUyoung commented Jun 15, 2019 •
It have the same problem here.
I have check the browser response(F12 tool), it show that «Failed to load resource: net::ERR_BLOCKED_BY_CLIENT»
So, it should be the client side that cause the problem.
zbarry commented Jun 24, 2019
My solution to this problem for people’s reference is to set up an ssh tunnel. If your Jupyter Lab server is running on port 8888, for example, you’d open up a terminal on your local machine you are connecting to the remote server on and run:
You would then connect to localhost:8888 in your web browser.
jeffheaton commented Jul 10, 2019
I get this as well, once I have more than about 6 notebooks open. Save starts to fail, which is really annoying, as copy/paste becomes the only lifeboat for stranded code. Once I bounce Jupyter Lab, all is fine again (until too many notebooks are opened again).
cammclean182 commented Oct 4, 2019
cammclean182 commented Oct 4, 2019
eliot1785 commented Dec 7, 2019
ayyyee commented Jan 31, 2020
I experienced the same situation. The name of the notebook seems to be the problem. Tried to create a new notebook with the name «analytics-v1» and it failed. Deleted it, created a new one called «analytics_v1» and it worked.
SandervandenOord commented Mar 4, 2020
I experienced also ‘Failed to Fetch’. This was caused by my filename containing two underscores: Pandas_Basics_Introduction.ipynb results in Failed to Fetch, but when I rename this to PandasBasicsIntroduction.ipynb it works again.
RachelOwl commented Jun 23, 2020
tharmaman commented Aug 14, 2020 •
Can confirm its related to specific names not being able to be used anymore.
ExampleName.ipynb didn’t work, names that work were: Example_name.ipynb or ExampleName1.ipynb
However oddly enough exampleName.ipynb did not work as well
Probably related to the name being attempted to save before but then something got corrupted barring you from ever using that file name again in any case pattern. Might be some weird caching mechanism that’s used.
Choumingzhao commented Sep 11, 2020
My solution to this problem for people’s reference is to set up an ssh tunnel. If your Jupyter Lab server is running on port 8888, for example, you’d open up a terminal on your local machine you are connecting to the remote server on and run:
You would then connect to localhost:8888 in your web browser.
Tried this solution with xshell’s ssh tunnel on Windows and it worked. It seems that this bug was caused by network related problems.
uncrayon commented Oct 2, 2020
I think that this error has many sources but one identified for me is one originated by ads-blocker plugins or any other pop-ups blocker plugin.
I simply turned off in all localhost. It works in Chrome and Firefox.
I didn’t identify why this kind of plugins cause this problem but it was almost a reproduction of Failed to load resource: net::ERR_BLOCKED_BY_CLIENT commented before by @NCTUyoung
I hope this can be of use to all of you.
aldomann commented Nov 10, 2020
Can confirm that uBlock Origin was causing the issue for me, as suggested by @uncrayon
cchwala commented Apr 24, 2021
Note that I resolved a similar issue by «trusting» my notebook. See my answer in this issue
jonathanbranam commented May 20, 2021
I just ran into this issue opening a file called mixpanel.py in the Brave browser and resolved it by turning off Brave’s protections for JupyterLab. Thanks to all the comments I was able to solve it quickly!
Nanguage commented Jun 25, 2021
I experienced the same error. Both jupyter lab and notebook can not save changes and autosave failed. There are no error message in the backend console. 
uncrayon commented Jun 25, 2021 •
@Nanguage I had the same problem before with jupyter lab. Is it nodejs and npm updated?
Nanguage commented Jul 2, 2021
@Nanguage I had the same problem before with jupyter lab. Is it nodejs and npm updated?
It’s not works for me, still have this bug after update node and npm.
uncrayon commented Jul 2, 2021
@Nanguage do you have the node lts version? I had to install manually the package (I use debian), the apt-get version was deprecated.
Also, do you use anaconda or did you install jupyter lab via pip? Do you use an env?
pnfnp commented Jul 2, 2021 •
For me it’s always happening when I try to save the file after showing a plotly Figure
nodejs=v14.17.2 and npm ✅
After a few minutes the file was saved correctly. But the response times increased for notebook load or cell execution or interaction.
Nanguage commented Nov 14, 2021 •
@Nanguage do you have the node lts version? I had to install manually the package (I use debian), the apt-get version was deprecated.
Also, do you use anaconda or did you install jupyter lab via pip? Do you use an env?
Here is the version info:
I’m using conda environment and install jupyterlab with pip.
My browser is chrome. I opened the debug tools and found these message:s 