Hi gleamtech team, any update on this ?
I've encountered same error while previewing my document on ios device as well.
But using android device with same environment, the document can be previewed

When you report an issue, specify your DocumentUltimate version. For example, v6.x and v7.x are very different in rendering and device support.

For example, you need to update to v6.9.8 (released 9 months ago) which is the last version if you have a v6.x license to fix mobile device problem:

For v7.x, there should be no problems.

Hi, we're using version GleamTech.7.1.5.0.
And we can't preview document on ios devices, but on android devices there is no problem. 

Here is the result from ios and android when previewed the file (using same environment) :

  

Before we're using gleamtech 6.9.7 and the preview document was fine on all iOS device.

After we upgrade to gleamtech7.1.5 the preview document seems can not work anymore on some iOS device. 

And we're using the preview document in our mobile app, so I think we can't switch to another browser since the preview is inside the app.

Any suggestion for our case ?

What is the exact iOS version you have on the phone? Maybe we can implement a fix for it. Yes v6.x supported older browsers but v7.x has modern rendering which requires some new JS features in the browser.

I'm using iOS 15.4.1 personally, but high probability our users might use lower version of iOS version. Most of our users are workers and not often to buy a new phone.

And I just receive feedback from one of our user (using iOS 18.2.1), also intermittently can not preview the document also. Sometimes can, but sometimes can not. 

Hi Cem, any update for this case ?

Yes, I examined the issue. It works as expected on Safari iOS 16.4. It's complaing about JS syntax errors on Safari iOS 15.4 thus the viewer is not rendered. The error in the console is below, to be specific:

SyntaxError: Unexpected token '{'

This is due to underlying PDF.js library's requirement of iOS 16.4, i.e pdfjs-dist builds for latest versions (v4.x) has JS compiled for "Safari >= 16.4" which means it needs JS syntax and features supported after that version.

When I recompiled pdfjs for "Safari >= 15.4", it works (no JS errors) but this time our CSS theme is not properly supported (viewer looks glitched). 

So it's hard to support iOS 15.x (it's from 2021, 4 years old) so I am not sure if it's worth the hassle to support.

so, will it be fixed or how ?
because majority of our users using low end mobile phone ios (ios < 16.4)

Hi Cem, there's feedback from our users using iOS 18.3.

Sometimes the document preview can be shown, and sometimes it can not be shown on iOS device.

I don't know if it's related with previous issue. Can you help to check it ?

Below I attached the video, can be seen when the document sometimes can not be previewed and iOS version is 18.3 at the end of video.