cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
mfreedman3
Community Participant

Disappearing Graphics

Jump to solution

I have jpg images which display just fine, then for no apparent reason they disappear, only showing the file name.  Is this a bug? Am I doing something wrong?

279413_pastedImage_1.png

146 Replies
mfreedman3
Community Participant

Thanks, Renee. I will work to assist with these guidelines...

jonesn16
Community Champion

Just to help illustrate the scope of this issue, images will sporadically fail to load. It happens:

-across different browsers

-across different networks

-across different computers, Mac and PC

-across different instances of Canvas ( I use Canvas for my job at one institution and I am a grad student using Canvas at a different institution)

-across different Canvas logins (my coworkers/faculty I work with have also experienced this)

Clearly this is an issue inherent to Canvas. What was upsetting is when I contacted Canvas tech support I was told that I should expect to clear my caches as a regular part of Canvas as a regular part of use. Which is ridiculous. My school just transitioned from Blackboard, and  trying to imagine how the initial sales pitch would have gone if the Instructure guy giving a demo had said “also, you’ll need to teach all your students and faculty how to manually clear their caches.”

I’m salty for two reasons: first, because in so many ways I think Canvas is a dramatic improvement over our old LMS, so this problem stands out even more. Second, I’m really surprised by the lack of an effective reaction from Canvas support. 

karen_bowden
Community Contributor

In reply to "Renee Carney@ Michael Freedman on Jun 22, 2018 12:59 PM

We saw those, Michael, but a screenshot doesn't help us troubleshoot this issue - so doing an all call for more screenshots will not help us solve this.  We need a link to the course with the problem element, and we need to know who was having the problem and if possible what tech they were using.  The ideal way to submit this ticket is to go to (or have the user go to) the problem element and use the help menu to 'submit a ticket' from that location.  It gives our support team invaluable information."

Unfortunately, Renee, it won't help to send a link to the course each time because within moments the image is sometimes "magically" there again.

A possible solution to help Canvas Support see this intermittent problem is to call (on the phone) Canvas Support when we see the issue on our screen. Then connect via a web conference and share our screen so they can see the problem as it happens. What they will probably see (finally) is what we see.

The image is not there.

Then it's there. 

We've been experiencing this problem where I work, too. To help stop the problem we are doing two things:

1. We stopped using images connected to Flickr. Instead, we upload our own or they are added during a course import. (I read the above post where it is now advisable to then go in to the new course, delete the images and re-upload them.)

2. If it's a "button" I've shown and offered our department team the option to use HTML instead of an image. 

Regarding support, I'd be curious to know if anyone has pulled a report showing the number of incidents related to the problem.

How many times has this problem already been reported from various customers?

What is the root cause in each situation?

Has a pattern been discerned yet?

I'm sure the people working on the Support team are just as frustrated by this problem as we are. However, the elusiveness of the issue is the obstacle.

Canvas is already a great product. We are trying to help make Canvas the best product possible. 

chofer
Community Coach
Community Coach

Hello everyone...

I'd like to re-summarize my post from last week.  It seems like many of you are saying this is an issue on Instructure's end.  While I cannot say for certain one way or the other if this is the case, I can tell you that working with our IT staff on-campus resolved broken image issues that cropped up for us recently.  And, it may be worth investigation on your end to talk with your IT folks to see if there are similar issues that need to be addressed.  The information I'm providing here is from one of our IT networking staff, so I won't be able to answer a lot of questions about this...I'm only providing the information.  I provided him with a Canvas page URL where broken images were occurring.

Conversation on June 18, 2018

  • It's possible that a related HOST was tagged as malicious by the IPS system.
  • s3.amazonaws.com was tagged as DNS malicious
    and I see one of the lookup addresses is instructure-uploads.s3.amazonaws.com.
    The information comes from Cisco Talos (threat logging intelligence groups), based on their security intelligence
    likely another host on the amazon web services s3 cluster was causing problems
    and the whole domain got tagged
  • Whitelisted the following: instructure-uploads.s3.amazonaws.com and s3.amazonaws.com in our IPS, because Cisco was reporting these DNS names as DNS Malware.
  • FYI - https://www.talosintelligence.com/reputation_center/lookup?search=s3.amazonaws.com
    About 3/4 of the way down the page: Blacklists
    Talos Security Intelligence Blacklist
    Blacklisted Yes
    Classification malware
    First Seen 2016-09-14T23:00:00 UTC
    Expiration Date 2018-06-18T16:46:24 UTC

Once he whitelisted these, our images re-appeared in our courses and on the Canvas Dashboard.

stelpstra
Community Champion

Chrome, Firefox and other browsers offer out of the box the ability to view and export underlying network traffic of a specific webpage. To understand this stuff and make sense of it you (or a helpful colleague) have to be quite an experienced techie (Instructure has lots of those :smileygrin:)

Here is an example of what you could see:

See Network Monitor - Firefox Developer Tools | MDN 

This way you can see all the traffic that make up the page.

It is also possible to export this to a HAR file to be analysed in different tools.

This illustrates how that would work:

To analyse a HAR file in full detail you can use this viewer: http://www.softwareishard.com/har/viewer/ 

Also take a look at HTTP response status codes - HTTP | MDN.

Note that 304 Not Modified is related to browser cache.

Note that this only works locally on the browser in which the page is loaded, as nobody can access this remotely due to browser security.

Be aware that this HAR file can contain sensitive data such as tokens and possibly privacy related data, so be careful who you send the HAR file (or screenshots of it) to.

b_w_reid
Community Participant

We too have intermittently experienced this issue. I use chrome, and some days the pictures load, and others they don't. I'll post this to support when it occurs again!

ysmalls
Community Champion

 @chofer ,  

Thanks for the information which might come in handy if this continues next year.  I did not have this happen in a while but it has happened and I was not able to give my teachers a reason why that was happening.

tuk03990
Community Member

Has this continued to work?

So far, so good,  @tuk03990 .  Smiley Happy

dholton
Community Participant

Run the Validate Links tool under Settings and it will find any broken images, files, or links in a course: How do I validate links in a course?  

Copy and paste won't work from course to course even if you uploaded the file or image to both courses because it generates a unique ID number for each file.