Dropbox images not showing in Posts on mobile devices

[Dave En Velo]

I have just noticed that my SMF Postings that contain images as shared Dropbox links are not displaying on my phone or tablet (both iOS) but are displaying fine on the Windows 10 desktop.  I am not sure if this is new behaviour or has always happened, I started to use Dropbox images around the end of January 2021.  I am posting to a private SMF 2.0.17 that is largely vanilla with Theme Settings of Default Theme - Curve (2.0.14) and Core Theme (2.0.16).

Below is an example of what I originally entered in posts to show an image:

Code Select Expand

[IMG]https://www.dropbox.com/s/tk0v15y3j6zajm8/2021031113222884019.png?raw=1[/IMG]

On investigation I have discovered that by tweaking the Dropbox URL I can get the images to appear in both environments.

Below are three versions of the URL:

• Version 1 is as shown above
  
• Version 2 has http replaced by https
  
• Version 3 has www.dropbox.com replaced by dl.dropboxusercontent.com  (I got this idea from community post https://www.simplemachines.org/community/index.php?topic=559714.msg3967950#msg3967950

In this forum I can see all three images using the Windows 10 desktop.  Using an iPhone or iPad I do not see the first image.  It is possible that this is a fault with the SMF theme but I am more inclined to believe a change in behaviour by Dropbox and I submit this posting in case it is useful to others.  My short-term fix is to alter my postings to use version 3.

version 1

version 2

version 3


Note that I did try adjusting the image URL to end with dl=0 or dl=1 instead of raw=1 but this had no impact on visibility in the iOS environment.

[shawnb61]

The http version does not exist.  There is a redirect that redirects you to the https version, which is why you can see it. 

I believe you have a security setting in the ios apps somewhere that is not allowing redirects.

You should really use the https version.  First, because it exists!  Also to avoid padlock issues, where that page looks insecure to your site visitors, since it has http content on it.

[Dave En Velo]

Thanks to shawnb61.  I agree that it is better to use https rather than http, which is why I have gone for version 3 which uses https. 

However, one of us is missing something.  The problem is with version 1 which does use https and displays fine under Windows 10 but does not display under iOS (Safari, Chrome or Firefox).  It may be a redirect issue but that seems strange when the URL in version 1 starts https://www.dropbox.com and version 2 uses redirect (to https) and works fine.  Also I cannot see anything in the iOS settings of Safari, Chrome or Firefox that might be inhibiting redirects.

There is something subtle going on and it may be related to redirects but I would be grateful for a bit more help in understanding the subtleties.

Of course it may be as simple as Dropbox does not support this use case. There is a suggestion that they dropped support in 2016.  https://help.dropbox.com/files-folders/share/force-download

[shawnb61]

• Version 2 has http replaced by https

Sorry I took the above literally.

It may be a redirect issue but that seems strange when the URL in version 1 starts https://www.dropbox.com and version 2 uses redirect (to https) and works fine.  Also I cannot see anything in the iOS settings of Safari, Chrome or Firefox that might be inhibiting redirects.

There is something subtle going on and it may be related to redirects but I would be grateful for a bit more help in understanding the subtleties.

If you want to learn the subtleties, you should look right at the headers.  You can do so within most browsers' dev tools, looking under the Network tab & selecting the line for the image.  LOTS of info on redirects & what's allowed & what's not allowed.  Your browser often only shows the last redirect though.

When diagnosing image proxy issues, I used this utility, that attempts to load images multiple ways & displays all the headers received along the way.  It is more clear using this tool when there are multiple redirects.  It is intended to emulate loading an image from your forum, & as a result, should be run from your forum's root folder:
https://github.com/sbulen/sjrbTools/blob/master/SMF_Img_Proxy_Diag.php

If you use the tool above, you will see that the first link has layers of redirects.  It may be a simple matter of "too many redirects" for that browser. 

One way to test that might be to check the option noted here & seeing if it makes a difference:
https://support.securly.com/hc/en-us/articles/360000881087-How-to-resolve-the-too-many-redirects-error-on-Safari

[Dave En Velo]

shawnb61 is quite right I have mistyped my problem description for version 2, it should be

• Version 2 has https replaced by http

apologies for the confusion. 

Thanks for the information on the SMF tool, the link to the post by Securly and the suggestion to look at the browser dev tools.   I have briefly looked at the Securly information and on the surface the suggestions do not seem to help.  As well as Chrome, Firefox and Safari under iOS I also tried the Edge and Puffin browsers and strangely the Puffin browser was able to see all three images.    I will start to look in more detail using the SMF tool and browser dev tools and hopefully I will get to the bottom of what is going on.

Thanks again.

[shawnb61]

I would open a trouble ticket with Dropbox.

That first link appears to be in line with their documented solution.

But it definitely doesn't show up on my ipad.  And there's a lot going on there with redirects.

I think they have an issue to fix.

[Dave En Velo]

I have posted the problem on the Dropbox Community site.  Whilst I have not got a response the system has pointed me a blizzard of related posts.  It would appear that it is this week's problem and there are a lot of upset Dropbox users.  My understanding from reading a few of these posts is:

• 
  This is the second time in the last few years that Dropbox have deprecated a feature that means users need to update old posts if they want images to be visible.
  
• It is probable that this problem is related to Apple action on redirects and a solution is unlikely to be forthcoming from Apple or Dropbox.
  
• For now the recommended approach to Postings with images in Dropbox is to use the approach I describe for version 3 above, i.e. replace www.dropbox.com in the link with dl.dropboxusercontent.com and ensure that any ?dl=0 or ?dl=1 in the link are changed to ?raw=1
  
• There is no easy workaround for existing postings.  Some bulletin boards are considering patching their software/databases to dynamically adjust Dropbox image links.
  
• There is not a lot of confidence that this problem will be fixed quickly, if at all, and some concern that the current recommended approach for Dropbox images in Postings may not have a long-term future - as far as I can see there is no formal response from Dropbox on this issue.
  

So I would say that shawnb61's analysis is spot on.

[Dave En Velo]

It appears that on Monday March 22, 2021, Dropbox rolled out a fix, and it does seem to work as evidenced by all the images in my original post now visible under iOS.  I have not found any official Dropbox comments on this issue.  The only link I can find confirming the fix is from another complainer in the Dropbox community.  So the problem is solved for now. 
https://www.dropboxforum.com/t5/Dropbox-files-folders/My-images-don-t-load-on-mobile/td-p/500870/page/11