Khan Academy human biology exercises missing images

We have just discovered that the graphics in the exercises/quizes for Khan Academy mitosis and mieosis are missing. I checked in Studio as well and the images are missing there. I have checked this on iOS and Mac OS, Safari and Firefox.

Thank you,

Hi Chris,

Thanks for brining this to our attention.

Could you point us to exact URL of an exercise that has this problem so we can look into it further?

I did a quick check on this exercise and saw the images showing up:

Note the above link is to version 14 of the channel, and it is possible the images-not-showing-up-in-exercises problem is from an earlier version of the channel (I remember we fixed some issues like that last year). Perhaps you need to update the version of the KA English channel you have on your device.



Thanks for your reply. I’m not sure how to select the exact URL. However, this is what I have for Mitosis questions:

I have also just discovered that the PLIX resources are not displaying on our predominantly used iPad2s running iOS 9.3.5. PLIX resources load on later iOS devices such as iPad Air running iPadOS 13, as well as MacOS Safari and Firefox. There is a recurrent error message indicating the page had problems and needs to reload, but never succeeds. Then it is stuck and can’t get out back to the home page.

Example PLIX resource: http://kolibri.jv:8080/en/learn/#/topics/c/58bad5e419244075b44b5d7d4c400ed2

Also, that channel we created was made just a few weeks ago, so I believe it is the most current Khan content.

Also, that channel we created was made just a few weeks ago, so I believe it is the most current Khan content.

Thanks for pointing that out. Do you know if the “Form 4 Human Biology” channel was created by importing straight from the Khan Academy channel, or perhaps from an intermediary curated channel. If it is imported directly from the KA English channel you are right it should be the latest/most recent, however if there was an intermediate curate channel, then it’s still possible it night have the old content.

Please let me know the iOS version, browser version, Kolibri version. It’s possible the two issues are linked (some browser+OS combination incompatibility).

Do the Mitosis exercises render right in the newer version of the iPads?

For reference, here is a link to the Mitosis question in the KA channel


The Mitosis and Meiosis exercises do not show up on any device, no matter version or browser.

The Form 4 Human Biology content was taken directly from the Khan Academy channel on Studio.

As for PLIX content, it is only the older iOS 9.3.5 that is not working. This has happened before with HTML5 books such as African Storybook content on this older iOS platform. BTW, doesn’t matter which browser one uses on iOS because all browsers are requiredby Apple to use the builtin iOS webkit as their engine. As I’m typing this to you, the PLIX book “Temperature Transitions” is in a loop of trying to load, giving error “A problem occured with this webpage so it was reloaded,” then trying again. It finally failed with "A problem repeated occured on… lengthy URL.

Here’s the details of our Kolibri system: Version: 0.13.2
OS: Linux-4.19.69-v7±armv7l-with-debian-9.11
Python: 3.5.3
Installer: kolibri(apt) with kolibri-server Version: 0.3.8~beta2-0ubuntu1
Server: nginx/1.10.3
Database: /home/pi/.kolibri/db.sqlite3
Device name: raspberrypi
Free disk space: 56 GB
Server time: Fri May 29 2020 19:50:47 GMT+0100 (WAT)
Server timezone: Africa/Douala

Hi Chris,

Also, that channel we created was made just a few weeks ago, so I believe it is the most current Khan content. […] The Form 4 Human Biology content was taken directly from the Khan Academy channel on Studio.

I imported the Form 4 Human Biology channel into a demo server here, and indeed the Mitosis question is missing the images:
This leads me to believe that the version of KA exercise might not be from the lates KA English channel (where it is working correctly).

Could you please try using the SYNC button on your channel. This should update the exercises and all files in the channel with the latest version.

After SYNC completes (note it might take a while) and you PUBLISH a new version, I’m hoping the exercise will be fixed.

Yes, that did the trick! Thanks. In the future, what should I do to try to resolve such problems if they occur again?


Some additional info on the issues with PLiX content. Example problem lesson:
“Thermal & Kinetic Energy (PLiX)”. As stated above, the content does no load at all on iOS 9.3.5 (iPad2). It does load on other devices with more current iOS and other operating systems.

However, challenge #2 of 5 in this particular exercise does not load correctly. The first image shows what it looks like on up-to-date MacOS. The answer box under the dotted line is missing. Dragging the answer down below the dotted line does not reveal where the answer should go. Also does not appear in up-to-date version of Firefox 76.0.1 (64-bit) on MacOS 10.14.6.

The image below is what the answer box should look like. Screenshot taken from Studio preview:

Hi @cjackson I can confirm the PLIX rendering issue (the drag and drop interaction on CHALLENGE 2/5) is somehow broken (no droppable area). I didn’t see any significant errors in the console but I’ll flag for colleagues who know more about javascript than me. Note as this is an actual content issue it will require longer to debug fix, and update the CK-12 channel.

I will post here when I have updates.

No problem. Thanks for your effort.


I have another exercise missing an image:

The red circle indicates where the image should be.

I deleted the exercise, reimported from the Khan Academy English channel, synced to my local system, but still no image.

Hi @cjackson

synced to my local system, […]

Do you mean UPDATE CHANNEL in Kolibri? One possible cause for this issue is Kolibri UPDATE CHANNEL process is not pulling in the latest images. You can debug this this by deleting the channel completely and importing again, instead of using the UPDATE CHANNEL option.

Here is the “Cohesion, adhesion, and surface tension” exercises in the latest version, where the images seem to be working:

Perhaps you can try running SYNC on your “Form 3 Biology” channel? Let me know if that fixes it.

reimported from the Khan Academy English channel

Could you please provide more details for how you do this step in Studio (maybe with screenshots).
I want to understand how it is possible to still get the old versions. There might be a bug in Studio.


I’ve come across another exercise that lacks the images:

It is the Prokaryotic and eukaryotic cells exercise from Khan Academy biology.

Do you have specific steps I can take to solve these problems as I come across them?


I have just created a channel on Studio of “Wireless Philosophy” from Khan Academy English content, then downloaded that channel. None of the exercises have the questions in them. These are found in the Critical Thinking folders.

Is there something I’m not doing correctly?

What do you mean exactly by this? In Kolibri you try to open an exercise and you don’t see anything show up? Do you see any errors being reported in the javascript console? [you can try from several different browsers and client devices]

Did you see any errors during the import process? [if so you can try deleting the channel and re-importing might help]

I imported your channel on this demo server and exercises seem to render fine.

Please provide info about Kolibri version, device, and browser. I suspect it is some iOS compatibility problem again.


Thanks for asking for clarification. Below is a screenshot of one of the exercises where no questions are showing. As far as I know, I didn’t have any errors in the download.

Here is technical details of my system:

Version: 0.14.0b3
OS: Linux-4.19.69-v7±armv7l-with-debian-9.11
Python: 3.5.3
Installer: kolibri(apt) with kolibri-server Version: 0.3.8~beta2-0ubuntu1
Server: undefined
Database: /home/pi/.kolibri/db.sqlite3
Free disk space: 45 GB
Server time: Mon Jul 06 2020 16:00:35 GMT+0100 (WAT)
Server timezone: Africa/Douala

Version: 0.14.0b3

Ah yes, there were some problems with an early 0.14 betas, which might be causing this.
Could you please see what happens with the latest beta = v0.14.0-beta7

Note: I would recommend using only the official releases (currently latest is 0.13.3) for “production” deploys, since they undergo extensive testing and checks before taking off the beta flag.

yes, failure on my part on the upgrade to beta. I’ll give beta7 a try and see what happens.

updating to 14.0-beta7 fixed the problem with the exercises. Also required to clear the cache of the browser.

The other pre-existing problem with missing images from some biology exercises continues, though. This is from Form 3 Biology > Cells > Prokaryotic and Eukaryotic Cells

Two exercises: Prokaryotic and eukaryotic cells, questions 7-12;

Eukaryotic cell structures, questions 3 & 5

Not sure what I need to do to fix this. I believe there are other exercises missing images, so if I can know how to resolve this problem, then I can take care of it from my end.