GitHub Pages requests intermittently hang without an HTTP response

[MicrosonicSolutions]

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I’m experiencing intermittent failures when accessing my GitHub Pages website. GET requests sometimes hang without returning an HTTP response, leaving the previous page displayed in the browser.

Affected website

• https://www.cumnorhurst.org.uk/
• https://microsonicsolutions.github.io/

The site is hosted using GitHub Pages. I temporarily configured GitHub Pages to publish the CumnorHurst site directly at microsonicsolutions.github.io to investigate whether the custom domain was responsible. The site initially loaded successfully, but the same intermittent failure occurred again. This suggests the problem is not limited to the custom domain.

Browser behaviour

I use Firefox on Windows. When I click a link to an affected page, the previous page remains displayed as though the link has not been followed. Firefox’s Network panel shows the corresponding GET request remaining incomplete, with no HTTP status or response data.

Eventually, the tab’s loading spinner stops, but the requested page has not loaded and the previous page remains visible. After the failure, the address bar still shows microsonicsolutions.github.io, rather than the requested path such as /about/. I also noticed that a padlock appeared beside the hostname around the time the spinner stopped. I mention this as an observation, not as evidence of a specific TLS or HTTP failure.

HAR evidence

I captured a HAR file from Firefox 157.0.1. One failed request was:

• URL: https://microsonicsolutions.github.io/about/
• Timestamp: 10 October 2026, 11:47:15.014 BST (10:47:15.014 UTC)
• HTTP status recorded: 0
• Response headers and body: none recorded
• Request and response protocol fields: empty
• Recorded request timings: all zero

I understand that these HAR fields do not establish exactly where the request is failing, but they show that Firefox did not record a normal HTTP response for this navigation.

Tests already performed

• DNS records appear consistent with a standard GitHub Pages configuration.
• Repeated command-line GET requests using curl over IPv4 completed successfully.
• Repeated command-line GET requests using curl over IPv6 also completed successfully.
• Repeated HTTP/1.1 requests, including connection reuse within each curl process, completed successfully.
• A friend in another county, using a separate internet connection, has also experienced similar failures.

These tests have not reproduced the browser failure consistently, so I suspect the issue may involve an intermittent interaction with the browser, connection handling, or the GitHub Pages/CDN delivery path. I cannot yet identify the cause.

Request for help

Could someone advise how best to investigate this, or whether there is a known issue affecting GitHub Pages requests that hang without returning an HTTP response?

In particular, I would appreciate advice on what additional diagnostics would help distinguish a browser/protocol issue from a GitHub Pages or CDN/edge issue.

I can provide the HAR capture privately if there is an appropriate way to do so. I have not attached it publicly because HAR files can contain sensitive request information.

Thank you.

[mengab77]

https://deepmind.google/blog/alphagenome-atlas-a-predictive-map-of-every-possible-dna-letter-change-in-the-human-genome/

[MicrosonicSolutions]

Additional diagnostic evidence from Microsoft Edge NetLog

I captured an Edge NetLog while reproducing the intermittent hang on https://www.cumnorhurst.org.uk/management/.

The log shows:

The browser established an IPv6 TCP connection to 2606:50c0:8002::153:443 and successfully negotiated TLS 1.3 and HTTP/2.

The existing HTTP/2 connection successfully served several earlier requests, including /about/, /site.css, /volunteering/ and /events/.

At approximately 13:22:33 BST, Edge sent an HTTP/2 ping and a GET request for /management/ over that existing connection.

No incoming socket data is recorded during the following 10 seconds.

At approximately 13:22:43 BST, the HTTP/2 session closed with ERR_HTTP2_PING_FAILED. Edge retried the request, which then received HTTP 200 from GitHub Pages in approximately 313 ms.

The log therefore points to a previously working, reused HTTP/2 connection becoming unresponsive, followed by a successful retry on a replacement connection. It does not establish whether the cause is at the CDN/server, in the network path, or elsewhere.

This is consistent with the intermittent hangs reported in Firefox and Edge, including by another user on a separate internet connection.

Can anyone advise whether this pattern is known to occur with GitHub Pages or its CDN, and what further evidence would help identify the cause?

[MalikAhed]

The Edge NetLog narrows this substantially: the request succeeded after a replacement connection, so the page content and DNS are unlikely to be the trigger. ERR_HTTP2_PING_FAILED means the reused HTTP/2 connection stopped receiving frames; the useful distinction is whether the old TCP/HTTP2 session is being dropped on the client path, an intermediary, or the Pages edge.

For a clean comparison, test the same URL in a fresh browser process and with curl --http2 -v --connect-timeout 10 --max-time 30, recording the resolved address, HTTP version, and UTC timestamp for each failure. Run a second control with curl --http1.1; if HTTP/1.1 remains reliable while HTTP/2 reproduces the stall, include that contrast in a GitHub Support ticket. Also capture the failing hostname, path, IPv4/IPv6 choice, and any request/trace ID visible in response headers.

As a temporary client workaround, a new connection (private window, browser restart, or switching networks) should avoid the stale session; disabling HTTP/2 can be used only as a diagnostic because it changes browser-wide behavior. The strongest escalation packet is the HAR/NetLog plus exact UTC timestamps, URL, protocol, address family, and a successful retry from the same machine. If this diagnosis helps, please click Mark as answer.

[MalikAhed]

The Edge NetLog narrows this substantially: the request succeeded after a replacement connection, so the page content and DNS are unlikely to be the trigger. ERR_HTTP2_PING_FAILED means the reused HTTP/2 connection stopped receiving frames; the useful distinction is whether the old TCP/HTTP2 session is being dropped on the client path, an intermediary, or the Pages edge.

For a clean comparison, test the same URL in a fresh browser process and with curl --http2 -v --connect-timeout 10 --max-time 30, recording the resolved address, HTTP version, and UTC timestamp for each failure. Run a second control with curl --http1.1; if HTTP/1.1 remains reliable while HTTP/2 reproduces the stall, include that contrast in a GitHub Support ticket. Also capture the failing hostname, path, IPv4/IPv6 choice, and any request/trace ID visible in response headers.

As a temporary client workaround, a new connection (private window, browser restart, or switching networks) should avoid the stale session; disabling HTTP/2 can be used only as a diagnostic because it changes browser-wide behavior. The strongest escalation packet is the HAR/NetLog plus exact UTC timestamps, URL, protocol, address family, and a successful retry from the same machine. If this diagnosis helps, please click Mark as answer.

[MicrosonicSolutions]

The issue now appears more frequent. A second Edge NetLog capture again shows ERR_HTTP2_PING_FAILED after a 10-second timeout on a reused HTTP/2 session. The associated socket log records outgoing data when the ping and GET are sent, but no incoming socket data during the timeout, followed by socket closure. The request subsequently retries successfully. The same general problem occurs in Firefox and has also been reported by a user on a separate ISP. This also occurs on the default github.io hostname, not only the custom domain.

[MalikAhed]

The repeat capture makes the case stronger: this is a reused HTTP/2 session failure that reproduces across browsers, domains, and an ISP, with a successful retry on a new connection. At this point the highest-value next step is a GitHub Support report with the two NetLogs, exact UTC timestamps, affected hostnames, IPv4/IPv6 details, and the fact that the replacement connection returns 200. Keep one curl --http1.1 control and one fresh curl --http2 run beside the captures so the protocol contrast is explicit. Until the edge/network path is identified, restarting the browser or forcing a new connection is the least disruptive workaround. If this answers the diagnostic question, please mark the earlier reply as accepted.

[MicrosonicSolutions]

thanks for responding.

during the period when firefox was stalled, i ran the following

for proto in --http2 --http1.1; do   echo;   echo "========== $proto ==========";    for i in $(seq 1 30); do     printf '%s ' "$(date -u +'%Y-%m-%dT%H:%M:%SZ')";      curl "$proto" -sS -o /dev/null       --connect-timeout 10       --max-time 30       -w 'http=%{http_version} status=%{http_code} ip=%{remote_ip} connect=%{time_connect}s tls_start=%{time_appconnect}s first_byte=%{time_starttransfer}s total=%{time_total}s\n'       https://www.cumnorhurst.org.uk/about/       || echo "CURL_FAILED exit=$?";      sleep 1;   done; done

and successfully obtained the result

========== --http2 ==========
2026-10-10T14:18:19Z http=2 status=200 ip=2606:50c0:8001::153 connect=0.053556s tls_start=0.111392s first_byte=0.149912s total=0.150319s
2026-10-10T14:18:21Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.013403s tls_start=0.054445s first_byte=0.069334s total=0.069563s
2026-10-10T14:18:22Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.016656s tls_start=0.068982s first_byte=0.084838s total=0.085090s
2026-10-10T14:18:23Z http=2 status=200 ip=2606:50c0:8002::153 connect=0.048647s tls_start=0.107654s first_byte=0.157614s total=0.157810s
2026-10-10T14:18:24Z http=2 status=200 ip=2606:50c0:8002::153 connect=0.041392s tls_start=0.095836s first_byte=0.135361s total=0.135536s
2026-10-10T14:18:26Z http=2 status=200 ip=2606:50c0:8001::153 connect=0.044116s tls_start=0.114437s first_byte=0.157742s total=0.157989s
2026-10-10T14:18:27Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.013949s tls_start=0.064608s first_byte=0.077194s total=0.077355s
2026-10-10T14:18:28Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.015449s tls_start=0.057958s first_byte=0.069461s total=0.069781s
2026-10-10T14:18:29Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.013525s tls_start=0.052320s first_byte=0.064609s total=0.064818s
2026-10-10T14:18:30Z http=2 status=200 ip=2606:50c0:8002::153 connect=0.044715s tls_start=0.095457s first_byte=0.137580s total=0.138533s
2026-10-10T14:18:31Z http=2 status=200 ip=2606:50c0:8002::153 connect=0.043911s tls_start=0.093305s first_byte=0.146015s total=0.146304s
2026-10-10T14:18:33Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.015608s tls_start=0.060462s first_byte=0.079497s total=0.079732s
2026-10-10T14:18:34Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.013565s tls_start=0.048012s first_byte=0.059898s total=0.060380s
2026-10-10T14:18:35Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.015654s tls_start=0.074651s first_byte=0.086233s total=0.086347s
2026-10-10T14:18:36Z http=2 status=200 ip=2606:50c0:8001::153 connect=0.039210s tls_start=0.093216s first_byte=0.127744s total=0.127943s
2026-10-10T14:18:37Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.015655s tls_start=0.063688s first_byte=0.075691s total=0.075861s
2026-10-10T14:18:39Z http=2 status=200 ip=2606:50c0:8002::153 connect=0.039250s tls_start=0.092661s first_byte=0.131530s total=0.131833s
2026-10-10T14:18:40Z http=2 status=200 ip=2606:50c0:8001::153 connect=0.037494s tls_start=0.090289s first_byte=0.127983s total=0.128177s
2026-10-10T14:18:41Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.017177s tls_start=0.065266s first_byte=0.076836s total=0.076935s
2026-10-10T14:18:42Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.018366s tls_start=0.056273s first_byte=0.068273s total=0.068509s
2026-10-10T14:18:43Z http=2 status=200 ip=2606:50c0:8001::153 connect=0.039891s tls_start=0.098228s first_byte=0.137150s total=0.144023s
2026-10-10T14:18:44Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.013664s tls_start=0.051012s first_byte=0.063716s total=0.063967s
2026-10-10T14:18:46Z http=2 status=200 ip=2606:50c0:8001::153 connect=0.037593s tls_start=0.113287s first_byte=0.151702s total=0.151884s
2026-10-10T14:18:47Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.014106s tls_start=0.059312s first_byte=0.070152s total=0.070262s
2026-10-10T14:18:48Z http=2 status=200 ip=2606:50c0:8003::153 connect=0.017477s tls_start=0.065884s first_byte=0.081237s total=0.081378s
2026-10-10T14:18:49Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.017376s tls_start=0.059859s first_byte=0.076357s total=0.076532s
2026-10-10T14:18:50Z http=2 status=200 ip=2606:50c0:8002::153 connect=0.041067s tls_start=0.088043s first_byte=0.127806s total=0.127938s
2026-10-10T14:18:51Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.016712s tls_start=0.057769s first_byte=0.069510s total=0.070156s
2026-10-10T14:18:53Z http=2 status=200 ip=2606:50c0:8000::153 connect=0.014825s tls_start=0.064240s first_byte=0.077600s total=0.077703s
2026-10-10T14:18:54Z http=2 status=200 ip=2606:50c0:8001::153 connect=0.036271s tls_start=0.084857s first_byte=0.123905s total=0.124074s

========== --http1.1 ==========
2026-10-10T14:18:55Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.056874s tls_start=0.115199s first_byte=0.153942s total=0.154004s
2026-10-10T14:18:56Z http=1.1 status=200 ip=2606:50c0:8000::153 connect=0.013487s tls_start=0.059261s first_byte=0.070851s total=0.071238s
2026-10-10T14:18:57Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.026974s tls_start=0.121038s first_byte=0.134846s total=0.135036s
2026-10-10T14:18:59Z http=1.1 status=200 ip=2606:50c0:8002::153 connect=0.042810s tls_start=0.098060s first_byte=0.137818s total=0.137951s
2026-10-10T14:19:00Z http=1.1 status=200 ip=2606:50c0:8002::153 connect=0.037778s tls_start=0.101655s first_byte=0.140314s total=0.140567s
2026-10-10T14:19:01Z http=1.1 status=200 ip=2606:50c0:8000::153 connect=0.029749s tls_start=0.081796s first_byte=0.093198s total=0.093385s
2026-10-10T14:19:02Z http=1.1 status=200 ip=2606:50c0:8002::153 connect=0.039757s tls_start=0.091350s first_byte=0.130662s total=0.130949s
2026-10-10T14:19:03Z http=1.1 status=200 ip=2606:50c0:8000::153 connect=0.011114s tls_start=0.059119s first_byte=0.069942s total=0.070124s
2026-10-10T14:19:04Z http=1.1 status=200 ip=2606:50c0:8002::153 connect=0.049390s tls_start=0.101957s first_byte=0.140135s total=0.140312s
2026-10-10T14:19:06Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.038539s tls_start=0.086309s first_byte=0.123633s total=0.123823s
2026-10-10T14:19:07Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.041442s tls_start=0.095846s first_byte=0.135190s total=0.135367s
2026-10-10T14:19:08Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.039696s tls_start=0.088435s first_byte=0.123780s total=0.123869s
2026-10-10T14:19:09Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.040972s tls_start=0.101863s first_byte=0.144001s total=0.144096s
2026-10-10T14:19:11Z http=1.1 status=200 ip=2606:50c0:8000::153 connect=0.012894s tls_start=0.049259s first_byte=0.060646s total=0.060836s
2026-10-10T14:19:12Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.042887s tls_start=0.092898s first_byte=0.130850s total=0.130973s
2026-10-10T14:19:13Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.013098s tls_start=0.054977s first_byte=0.066124s total=0.066288s
2026-10-10T14:19:14Z http=1.1 status=200 ip=2606:50c0:8000::153 connect=0.015518s tls_start=0.071243s first_byte=0.083194s total=0.083787s
2026-10-10T14:19:15Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.010510s tls_start=0.049475s first_byte=0.061706s total=0.061809s
2026-10-10T14:19:16Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.043219s tls_start=0.091643s first_byte=0.129991s total=0.130487s
2026-10-10T14:19:18Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.014302s tls_start=0.050614s first_byte=0.061674s total=0.062113s
2026-10-10T14:19:19Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.013046s tls_start=0.047320s first_byte=0.057602s total=0.058151s
2026-10-10T14:19:20Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.043030s tls_start=0.122324s first_byte=0.170105s total=0.170217s
2026-10-10T14:19:21Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.039883s tls_start=0.089765s first_byte=0.129837s total=0.130033s
2026-10-10T14:19:22Z http=1.1 status=200 ip=2606:50c0:8000::153 connect=0.014304s tls_start=0.056755s first_byte=0.066503s total=0.066749s
2026-10-10T14:19:23Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.014489s tls_start=0.049702s first_byte=0.058520s total=0.058782s
2026-10-10T14:19:25Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.013883s tls_start=0.097479s first_byte=0.109355s total=0.109528s
2026-10-10T14:19:26Z http=1.1 status=200 ip=2606:50c0:8000::153 connect=0.012807s tls_start=0.049166s first_byte=0.060444s total=0.060798s
2026-10-10T14:19:27Z http=1.1 status=200 ip=2606:50c0:8001::153 connect=0.039694s tls_start=0.090486s first_byte=0.129295s total=0.129662s
2026-10-10T14:19:28Z http=1.1 status=200 ip=2606:50c0:8002::153 connect=0.046860s tls_start=0.097658s first_byte=0.138560s total=0.139426s
2026-10-10T14:19:29Z http=1.1 status=200 ip=2606:50c0:8003::153 connect=0.014173s tls_start=0.057577s first_byte=0.069899s total=0.070157s

i'm guessing that curl wasn't trying to use the same "old" connection and so didn't hit the same issue as the browser

[MalikAhed]

@MicrosonicSolutions please mark as answered if it worked i am trying to get an achievement and i am 1 down :)