Amphtml: browser back can cause clicks to not working in AMP Cache

[tanakayuki]

What's the issue?

browser back can cause clicks to not working in AMP.
However, origin AMP is fine.

How do we reproduce the issue?

1. Open Google AMP Cache
2. Make transitions within the site
3. Browser Back to AMP Cache (AMP Viewer) <- (Click not working here)

What browsers are affected?

I think it will happen at least if you use safari or chrome on iPhone with OS version 13 or higher.

My Device

• iOS 13.5.1 iphoneSE NG
• iOS 14.1 iphoneSE NG

VM Device(browserstack.com)

• iOS 11 iphoneX OK
• iOS 12 iphoneXS OK
• iOS 13 iphone8 NG
• iOS 14 iphone11 NG

Which AMP version is affected?

Version 2010132225002

Screen Capture and AMP Cache URL

-

• https://www.google.com/amp/s/www.ikyu.com/sd/theme/a320701c2/amp/

• 

  • https://www.google.com/amp/s/akiba-pc.watch.impress.co.jp/docs/sp/1160/581/amp.index.html

• 

  • https://www.google.com/amp/s/www3.nhk.or.jp/nhkworld/en/news/20201023_14/amp.html

[uskay]

This seems to be a common issue we are seeing recently which is critical in reliability of the application. cc/ @nainar
Reference: https://github.com/ampproject/amphtml/issues/27691#issuecomment-716868604

[uskay]

cc/ @flaviori , @choumx and @ericfs
Have you seen this behaviour?

[ericfs]

Thanks for the detailed report. I think I was able to reproduce it.

Repro steps:

• Using Safari in iOS Simulator 13.4.1
• Open https://www.google.com/amp/s/akiba-pc.watch.impress.co.jp/docs/sp/1160/581/amp.index.html
• Click the "PC" link
• Navigate back
• Try to click the same "PC" link
  
  
  
  • nothing happens
  
  
• Scroll the page up and down
• Try to click the same "PC" link
  
  
  
  • It works
  
  

Long press to get a link preview does work:

As does selecting text.

This makes me think we may be hitting a browser bug of some sort.

I am not able to reproduce when using https://akiba-pc.watch.impress.co.jp/docs/sp/1160/581/amp.index.html
So it does seem to be something about showing the page in the AMP Viewer.

@jridgewell do you have any ideas here? I know Safari had some other scrolling related iframe changes so I'm wondering if this could be somehow related.

[mauricengo-revolve]

Wondering if there's any updates on resolving this issue and the one in https://github.com/ampproject/amphtml/issues/27691. This seem to be an issue for all AMP sites. Are these issues top priority?
@flaviori , @choumx and @ericfs

[ericfs]

I think @flaviori was looking to get someone to work on #27691.

For this one, I don't have any additional insight. Pinging @jridgewell for thoughts.

[ericfs]

I think this is very likely a Safari bug. One thing that may fix it is to programmatically scroll the page. Something like window.scrollTo(scrollX - 0.1, 0).

@dvoytenko, @jridgewell, who would be a good owner for this issue?
Are either of you in contact with Safari for other scrolling issues? It seems like this would be worth reporting.

[dvoytenko]

@ericfs Any possibility that this might be some sort of a glasspane in the viewer?

[ericfs]

Based on my observations, I don't think it is a glasspane. I can scroll within the iframe and once I scroll, I can click on links.