🐛 Bug Report — Browser Rendering Error Due To Compatbility Date

[apeacock1991]

If you create an empty project and add Browser Rendering to it that just goes to any page, but set nodejs_compat and compatibility date to 2026-03-17 or later, you'll get the following error:

✘ [ERROR] Uncaught RangeError: Offset is outside the bounds of the DataView Error

      at chunksToMessage
  (file:///Users/ashley.peacock/projects/schedule-scraper/node_modules/@cloudflare/puppeteer/src/cloudflare/chunking.ts:47:30)
      at null.<anonymous>
  (file:///Users/ashley.peacock/projects/schedule-scraper/node_modules/@cloudflare/puppeteer/src/cloudflare/WorkersWebSocketTransport.ts:46:23)

If you set the compatibility date to 2026-03-16 or earlier, everything will work fine so it looks like some sort of regression.

[danlapid]

Hey @apeacock1991
Shockingly enough there were 9 compat flags added on Mar 17th, it's also the date we disabled node compat polyfilling in wrangler completely.
This would be really interesting to debug.

I would love a repro so that we can test it out ourselves.
This is the list of new compat flags added on that date:

"enable_nodejs_perf_hooks_module", "enable_global_performance_classes", "enable_nodejs_v8_module", "enable_nodejs_tty_module", "enable_nodejs_child_process_module", "enable_nodejs_worker_threads_module", "enable_nodejs_readline_module", "enable_nodejs_repl_module", "websocket_standard_binary_type"

We might need to try to enable/disable each of them to see which one caused the regression.
Considering the stack trace I suspect it might be websocket_standard_binary_type

[apeacock1991]

Hey @apeacock1991 Shockingly enough there were 9 compat flags added on Mar 17th, it's also the date we disabled node compat polyfilling in wrangler completely. This would be really interesting to debug.

I would love a repro so that we can test it out ourselves. This is the list of new compat flags added on that date:

"enable_nodejs_perf_hooks_module", "enable_global_performance_classes", "enable_nodejs_v8_module", "enable_nodejs_tty_module", "enable_nodejs_child_process_module", "enable_nodejs_worker_threads_module", "enable_nodejs_readline_module", "enable_nodejs_repl_module", "websocket_standard_binary_type"

We might need to try to enable/disable each of them to see which one caused the regression. Considering the stack trace I suspect it might be websocket_standard_binary_type

👋🏻 @danlapid here's the repo with repro: https://github.com/apeacock1991/br-bug-example

Your hunch was correct, if I set compat date to 2026-03-16 and enable all flags except websocket_standard_binary_type it continues to work, but as soon as I add websocket_standard_binary_type it breaks with the error above!

[harrishancock]

@apeacock1991 thanks for the report!

This is a bug in our Puppeteer fork (and Playwright, too), confirmed here: cloudflare/puppeteer#193

As such, I'll close this, and we can track in that linked issue.

[apeacock1991]

@apeacock1991 thanks for the report!

This is a bug in our Puppeteer fork (and Playwright, too), confirmed here: cloudflare/puppeteer#193

As such, I'll close this, and we can track in that linked issue.

Thank you!

[harrishancock]

I'm going to re-open this issue until the downstream bug(s) are fixed. While there's no code changes for us to make in this repo, it's fair to say that it's our issue, too, and keeping it open helps communicate clearly that it's still a problem.

[harrishancock]

This is fixed downstream in our forks of puppeteer (v1.1.0) and playwright (v1.3.0), closing.

[apeacock1991]

This is fixed downstream in our forks of puppeteer (v1.1.0) and playwright (v1.3.0), closing.

Thank you!