What s the net ERR HTTP2 PROTOCOL ERROR about

Question

I m currently working on a website  which triggers a net  ERR HTTP2 PROTOCOL ERROR 200 error on Google Chrome  I m not sure exactly what can provoke this error  I just noticed it pops out only when accessing the website in HTTPS  I can t be 100  sure it is related  but it looks like it prevents javascript to be executed properly   For instance  the following scenario happens     I m accessing the website in HTTPS My Twitter feed integrated via https   publish twitter com  isn t loaded at all  I can notice in the console the ERR HTTP2 PROTOCOL ERROR If I remove the code to load the Twitter feed  the error remains If I access the website in HTTP  the Twitter feed appears and the error disappears    Google Chrome is the only web browser triggering the error  it works well on both Edge and Firefox   NB  I tried with Safari  and I have a similar kcferrordomaincfnetwork 303 error   I was wondering if it could be related to the header returned by the server since there is this  200  mention in the error  and a 404   500 page isn t triggering anything    Thing is the error isn t documented at all  Google search gives me very few results  Moreover  I noticed it appears on very recent Google Chrome releases  the error doesn t pop on v 64 X  but it does on v 75   regardless of the OS  I m working on Mac tho    Any clue at this point to investigate would be gladly appreciated    Thanks in advance   Tristan    Edit 1   Might be related to Website OK on Firefox but not on Safari  kCFErrorDomainCFNetwork error 303  neither Chrome  net  ERR SPDY PROTOCOL ERROR     Edit 2   Findings from further investigations are the following     error doesn t pop on the exact same page if server returns 404 instead of 2XX error doesn t pop on local with a HTTPS certificate error pops on a different server  both are OVH s   which uses a different certificate error pops no matter what PHP version is used  from 5 6 to 7 3  framework used   Cakephp 2 10      Edit 3   As requested  below is the returned header for the failing ressource  which is the whole web page  Even if the error is triggering on each page having a HTTP header 200  those pages are always loading on client s browser  but sometimes an element is missing  in my exemple  the external Twitter feed   Every other asset on the Network tab has a success return  except the whole document itself     Google Chrome header  with error       Firefox header  without error       A curl --head --http2 request in console returns the following success    HTTP 2 200  date  Fri  04 Oct 2019 08 04 51 GMT content-type  text html  charset UTF-8 content-length  127089 set-cookie  SERVERID31396 2341116  path    max-age 900 server  Apache x-powered-by  PHP 7 2 set-cookie  xxxxx 0919c5563fc87d601ab99e2f85d4217d  expires Fri  04-Oct-2019 12 04 51 GMT  Max-Age 14400  path    secure  HttpOnly vary  Accept-Encoding     Edit 4   Trying to go deeper with the chrome   net-export  and https   netlog-viewer appspot com tools is telling me the request ends with a RST STREAM    t 123354  st 5170     HTTP2 SESSION RECV RST STREAM                       -- gt  error code    2  INTERNAL ERROR                         -- gt  stream id   1   For what I read in this other post   In HTTP 2  if the client wants to abort the request  it sends a RST STREAM  When the server receives a RST STREAM  it will stop sending DATA frames to the client  thereby stopping the response  or the download   The connection is still usable for other requests  and requests responses that were concurrent with the one that has been aborted may continue to progress        It is possible that by the time the RST STREAM travels from the client to the server  the whole content of the request is in transit and will arrive to the client  which will discard it  However  for large response contents  sending a RST STREAM may have a good chance to arrive to the server before the whole response content is sent  and therefore will save bandwidth    The described behavior is the same as the one I can observe  But that would mean the browser is the culprit  and then I wouldn t understand why it happens on two identical pages with one having a 200 header and the other a 404  same goes if I disable JS

User · Answer

We experienced this problem on pages with long Base64 strings. The problem occurs because we use CloudFlare.

Details: https://community.cloudflare.com/t/err-http2-protocol-error/119619.

Key section from the forum post:

After further testing on Incognito tabs on multiple browsers, then doing the changes on the code from a BASE64 to a real .png image, the issue never happened again, in ANY browser. The .png had around 500kb before becoming a base64,so CloudFlare has issues with huge lines of text on same line (since base64 is a long string) as a proxy between the domain and the heroku. As mentioned before, directly hitting Heroku url also never happened the issue.

The temporary hack is to disable HTTP/2 on CloudFlare.

Hope someone else can produce a better solution that doesn't require disabling HTTP/2 on CloudFlare.

User · Answer

I also faced this error and I believe there can be multiple reasons behind it  Mine was  ARR was getting timed-out   In my case  browser was making a request to a reverse proxy site where I have set my redirection rules and that proxy site is eventually requesting the actual site  Now for huge data it was taking more than 2 minutes 5 seconds and Application Request Routing timeout for my server was set to 2 minutes  I fixed this by increasing the ARR timeout by below steps  1  Go to IIS 2  Click on server name 3  Click on Application Request Routing Cache in the middle pane 4  Click Server Proxy settings in right pane 5  Increase the timeout 6  Click Apply

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By default nginx limits upload size to 1MB  With client max body size you can set your own limit  as in location  uploads               client max body size 100M      You can set this setting also on the http or server block instead  See here   This fixed my issue with net  ERR HTTP2 PROTOCOL ERROR

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In my case I have a kubernetes cluster with nginx ingress controller and nginx php-fpm to handle drupal instance  I notice this issue on one of my page  where my pictures was not loaded in chrome  After investigation I discovered that modsecurity module enabled in my nginx ingress somehow produce this issue  Not fully know why  but after disabling it  all pages are loaded fine  Best Regards

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I m not convinced this was the issue but through cPanel I d noticed the PHP version was on 5 6 and changing it to 7 3 seemed to fix it  This was for a WordPress site  I noticed I could access images and generic PHP files but loading WordPress itself caused the error

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For my situation this error was caused by having circular references in json sent from the server when using an ORM for parent child relationships  So the quick and easy solution was   JsonConvert SerializeObject myObject  new JsonSerializerSettings   ReferenceLoopHandling   ReferenceLoopHandling Ignore      The better solution is to create DTOs that do not contain the references on both sides  parent child

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I experienced a similar problem  I was getting ERR HTTP2 PROTOCOL ERROR on one of the HTTP GET requests    I noticed that the Chrome update was pending  so I updated the Chrome browser to the latest version and the error was gone next time when I relaunched the browser

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In our case  the reason was invalid header  As mentioned in Edit 4   take the logs in the viewer choose Events chose HTTP2 SESSION  Look for something similar   HTTP2 SESSION RECV INVALID HEADER -- gt  error    quot Invalid character in header name  quot  -- gt  header name    quot charset utf-8 quot

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For me it was due to full disk space  My application  server  was running on docker  Cleared some space and it started working

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This error is currently being fixed  https   chromium-review googlesource com c chromium src   2001234  But it helped me  changing nginx settings    turning on gzip  add header  Cache-Control   no-store  no-cache  must-revalidate  proxy-revalidate  max-age 0   expires off    In my case  Nginx acts as a reverse proxy for Node js application

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I encountered this because the http2 server closed the connection when sending a big response to the Chrome   Why  Because it is just a setting of the http2 server  named WriteTimeout

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I hit this issue working with Server Sent Events  The problem was solved when I noticed that the domain name I used to initiate the connection included a trailing slash  e g  https   foo bar bam  failed with ERR HTTP PROTOCOL ERROR while https   foo bar bam worked

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I had another case that caused an ERR HTTP2 PROTOCOL ERROR that hasn t been mentioned here yet   I had created a cross reference in IOC  Unity   where I had class A referencing class B  through a couple of layers   and class B referencing class A   Bad design on my part really   But I created a new interface class for the method in class A that I was calling from class B  and that cleared it up

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I got the same issue  asp  c   - HttpPostedFileBase  when posting a file that was larger than 1MB  even though application doesn t have any limitation for file size   for me the simplification of model class helped  If you got this issue  try to remove some parts of the model  and see if it will help in any way  Sounds strange  but worked for me

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This happened to me when I registered a new domain name  e g    new  for example com  new example com   The name could not be resolved temporarily in my location for a couple of hours  while it could be resolved abroad  So I used a proxy to test the website where I saw net  ERR HTTP2 PROTOCOL ERROR in chrome console for some AJAX posts  Hours later  when the name could be resloved locally  those error just dissappeared   I think the reason for that error is those AJAX requests were not redirected by my proxy  it just visit a website which had not been resolved by my local DNS resolver

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I am finally able to solve this error after researching some things I thought is causing the error for 24 errors  I visited all the pages across the web  And I am happy to say that I have found the solution   If you are using NGINX  then set gzip to off and add proxy max temp file size 0  in the server block like I have shown below    server                 gzip off    proxy max temp file size 0    location         proxy pass http   127 0 0 1 3000            Why  Because what actually happening was all the contents were being compressed twice and we don t want that  right

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In my case it was - no disk space left on the web server

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I had this problem when having a Nginx server that exposing the node-js application to the external world  The Nginx made the file  css  js       compressed with gzip and with Chrome it looked like the same    The problem solved when we found that the node-js server is also compressed the content with gzip  In someway  this double compressing leading to this problem  Canceling node-js compression solved the issue

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I have been experiencing this problem for the last week now as I ve been trying to send DELETE requests to my PHP server through AJAX  I recently upgraded my hosting plan where I now have an SSL Certificate on my host which stores the PHP and JS files  Since adding an SSL Certificate I no longer experience this issue  Hoping this helps with this strange error

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I faced this error several times and  it was due to transferring large resources larger than 3MB  from server to client

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In my case  it was WordPress that now requires PHP 7 4 and I was running 7 2  As soon as I updated  the errors disappeared

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net  ERR HTTP2 COMPRESSION ERROR -  WORDPRESS Okay  I hope this will help many  I have been experiencing this for many weeks  My apology because I am using WordPress  net  ERR HTTP2 COMPRESSION ERROR only occurs on Chrome Incognito  I have Cloudflare for my CDN and caching HTML - and W3 Total Cache - for minify js  css and Page Cache  OP-Cache  Object Cache  Browser Cache  now  after countless of trouble shooting  I detected the issue when disabling the  quot Browser Cache quot  after that  I fixed the problem when I modified the Browser Cache   go to side panel   find the   quot HTTP Strict Transport Security policy quot   make sure its checked  under that is directive set the value to - max-age EXPIRES SECONDS  includeSubDomain  preload take note that I am using sub-domain

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I didn t figure out what exactly was happening  but I found a solution   The CDN feature of OVH was the culprit  I had it installed on my host service but disabled for my domain because I didn t need it   Somehow  when I enable it  everything works   I think it forces Apache to use the HTTP2 protocol  but what I don t understand is that there indeed was an HTTP2 mention in each of my headers  which I presume means the server was answering using the right protocol   So the solution for my very particular case was to enable the CDN option on all concerned domains   If anyone understands better what could have happened here  feel free to share explanations

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For several weeks I was also annoyed by this  bug    net    ERR HTTP2 PROTOCOL ERROR 200   In my case  it occurred on images generated by PHP   It was at header   level  and on this one in particular   header   Content-Length    Filesize  cache file      It did obviously not return the exact size  so I deleted it and everything works fine now   So Chrome checks the accuracy of the data transmitted via the headers  and if it does not correspond  it fails   EDIT  I found why content-length via filesize was being miscalculated  the GZIP compression is active on the PHP files  so excluding the file in question will fix the problem  Put this code in the  htaccess   SetEnvIfNoCase Request URI     thumb php no-gzip -vary   It works and we keep the header Content-length

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My team saw this on a single javascript file we were serving up  Every other file worked fine  We switched from http2 back to http1 1 and then either net  ERR INCOMPLETE CHUNKED ENCODING or ERR CONTENT LENGTH MISMATCH  We ultimately discovered that there was a corporate filter  Trustwave  that was erroneously detecting an  infoleak   we suspect it detected something in our file filename that resembled a social security number   Getting corporate to tweak this filter resolved our issues

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In my case  nginx on windows proxying an app while serving static assets on its own  page was showing multiple assets including 14 bigger pictures  those errors were shown for about 5 of those images exactly after 60 seconds  in my case it was a default send timeout of 60s making those image requests fail  increasing the send timeout made it work I am not sure what is causing nginx on windows to serve those files so slow - it is only 11 5MB of resources which takes nginx almost 2 minutes to serve but I guess it is subject for another thread

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For me  it was the StackOverFlow Exception because of recursive code

[google-chrome] What's the net::ERR_HTTP2_PROTOCOL_ERROR about?

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