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Failed Image Request in Dynatrace

shashank_b_agra
Organizer

Hi, I have a application which i am monitoring using agentless Js tag to perform real user monitoring. When i look into the application under "Top Errors" section, I am seeing lot of "Failed Image" requests but when i load those images in browser they gets loaded perfectly fine and also I am NOT seeing any errors in my apache access logs for those images.

So why Dynatrace is showing them as Failed Image request. This is creating a lot of confusion between developers and stakeholders whether to rely on this data or not.

 

Can someone shed light on this as what exactly it is capturing here?

shashank_b_agra_0-1631405567398.png

 

@ChadTurner @sebastian_kryst - Tagging you guys as you have responded & solved my queries most of the time. 🙂

Any help is appreciated.

6 REPLIES 6

Julius_Loman
DynaMight Guru
DynaMight Guru

If it works for you it does not necessarily mean it's working for everyone. The Failed images frequency in your case is really low. Does your app use a CDN? Is it publicly facing application or an internal one?

 

TEMPEST a.s., Slovakia, Dynatrace Master Partner

@Julius_Loman It's a public facing application and all the images are loaded like this - /join/static/img/WhyVM-Ultrafast.svg

 

Also as i mentioned, there are no errors in Apache logs, no 5XX no 4XX errors. If they are failing to load, it should appear in apache logs in Splunk

@shashank_b_agra No, they likely did not reach your server and that's why Dynatrace RUM reports broken images. Look at the user sessions which had those image errors. RUM measures that in the browser for the webapp. If something blocks it on the way to your host (adblocker/proxy/network/... anything), you won't see that in your Apache log.


TEMPEST a.s., Slovakia, Dynatrace Master Partner

ian_cervantez
Visitor

I'm seeing this too, might be a bug in the latest version of ruxitagent.

demvin
Newcomer

Seeing this too in our app.  Hypothesis is a cancelled image download due to subsequent navigation, but it's definitely not an app error in our case.  Pollutes Dynatrace though.

 

AntonioSousa
DynaMight Leader
DynaMight Leader

If you follow the 404 error in Dynatrace, you can then select "User actions affected by this error"->click on the user action, and then "Perform waterfall analysis". You'll then have the waterfalls where the errors happened. You might have additional clues there.

Antonio Sousa