"Chess basics" don't load on iPad

[KommX]

I just noticed that the "Chess basics" section doesn't properly load for me on two different iPads (tested Safari and Brave browsers). It works fine on an Android phone and my Windows computer.

Steps to reproduce:

1. Log out (so that you don't have any progress)
2. Go to https://lichess.org/learn#/
3. Choose any piece e.g. the rook - now the board appears in the background with the small overlay titles "Stage 1: The rook"
4. Hit "LET'S GO"

What happened?
I hear a sound but the overlay stays and the tab seems to consume a lot of CPU resources.

What I expected?
The exercise should load.

Tested on:

• iPad 6th Gen and iPad 8th Gen, both iOS 14.2
• most recent versions of Safari and Brave

[kraktus]

Can reproduce on IOS 14.2

[niklasf]

Can reproduce in Browserstack, but unable to get a stacktrace or logged errors.

[andylatham82]

Happens on an iPhone with both Safari and Chrome browsers.

[x4d3]

I can reproduce on my Iphone X and on an Ipad Mini.

[cuddlestmonkey]

Reproduced on iPhone SE (2020) with Safari and Chrome.

[unhammer]

On an iPad 2020 in both Safari and Firefox I can play the initial lessons (perhaps because they were already started on from a laptop?), but trying lesson 13 and 14 which I hadn't tried yet they seem to be giving this issue (I hear the sound on clicking the start button, but nothing happens).

EDIT: I managed to open lesson 13 on iPad Safari after first opening it once (under that user) from Linux Firefox. So I guess iOS users just have to do that to all lessons before trying them …

[andylatham82]

Still happening on iPhone, and now can confirm it happening on iPad.

[kraktus]

I cannot reproduce the issue (can click fine) locally. Could it be some sort of security measure trigged when the whole screen is clickable to avoid phishing?

[unhammer]

@kraktus try https://lichess.org/learn#/4 in a private tab (ie. not logged in to your user) on an up-to-date iPad with Safari.

I don't have a Mac, so unfortunately I can't get up web console (iPads truly are locked down :-/). I tried running weinre behind a cors-enabled https proxy to see if I could get some debug info, but unfortunately lichess's CSP disallows bookmarklets (no scripts-src), so someone with a Mac will have to look further into it.

[zeknas]

On an iPhone, this is the error :

Unrecognized Content-Security-Policy directive 'worker-src'

According to Mozilla, this is indeed not supported by Safari https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/worker-src#browser_compatibility

Hope this helps !

[unhammer]

https://github.com/ornicar/lila/blob/9c34d433f9979513066e9af547d1e2be02738cd5/modules/common/src/main/ContentSecurityPolicy.scala#L81 maybe remove this then? (can it be conditionally removed on safari?)

( ONLYOFFICE/onlyoffice-nextcloud#213 seems to have fixed it by adding a "*" as target arg to window.postMessage, but that's maybe equivalent to no csp?)

[niklasf]

No need, this is completely unrelated, as unrecognized Content-Security-Policy directives are ignored anyway.

[unhammer]

Isn't the issue here that Safari doesn't ignore the unrecognized directive?

[benediktwerner]

No, probably not. The actual problem in the issue you linked seems unrelated to the CSP. They were simply missing the required second parameter for postMessage.

[niklasf]

@benediktwerner Wow, your patch https://github.com/ornicar/lila/pull/8778/files (+ follow ups) seems to have fixed this issue, too.

[gphilip]

I apologize if it is not OK to comment on a closed issue, but: this issue is still present for me on my iPad. I get the exact same behaviour as originally described by @KommX . Tested on: iPad Air 4th Generation, iOS 14.5.1 . Most recent versions of Safari and Firefox.

[KommX]

@gphilip: That's weird, as it works for me now super fine.

[gphilip]

@KommX Thank you! I checked again, and I hadn't updated this OS version; it was still in the previous version. I updated the OS, and now this works perfectly for me.

Thanks once again!