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HTTP status codes 970-979

DynaMight Guru
DynaMight Guru

I have an application that started showing a lot of HTTP/971 error codes. Never had heard of these HTTP codes, looked online, didn't find anything.

Then I found in the UI that it referred to "Canceled". After some more searches, found a page in the documentation, in that these errors are specific to Dynatrace RUM 🙂

They are the following:



They can be configured to not affect Apdex, which they do by default in Applications created after version 1.238

Antonio Sousa

DynaMight Legend
DynaMight Legend

Great Tip! thanks @AntonioSousa 



Hello Antonio. So does that mean that these codes can be removed without problem for Apdex issues?

DynaMight Champion
DynaMight Champion

As always, I also got this exotic. Does anyone know some undocumented JS agent flags like cux = 0 that could help in this case and remove this status codes from application\affecting application?

Customer faced with problem that these JS codes impact on customer "best frontend code ever".


Alex Romanenkov


@Romanenkov_Al3x Did you remove them from the error detection rules for the web application?

Certified Dynatrace Master | Alanata a.s., Slovakia, Dynatrace Master Partner

Hi Julius.

I have already removed this rule, but it didn't help. Customers code works only without JS agent loaded on page. Problem related to file uploading when agent is injected and customer code look like works without "No response" http codes.

Dynatrace documentation:

For applications created with Dynatrace version 1.238+, the RUM JavaScript reports some request errors using custom status codes 970–979 when the real HTTP status code can't be captured. Note that these custom status codes are not real HTTP status codes; they just mean that the RUM JavaScript detected an error fired by the framework you use.


Customer wan't change his "very good code" because it's insanely expensive.

I have already checked behavior with extended log of JS agent loaded on page. Already checked all information from support archive and HAR sessions of problematic behavior.

Also - I have tried to exclude this page with injection rule. It also didn't help






So the issue is the web application does not work properly when RUM JS code is injected? 
Or do they complain about seeing the 97x errors in the waterfall?

Certified Dynatrace Master | Alanata a.s., Slovakia, Dynatrace Master Partner

Yes, the issue is that the web application does not work properly when RUM JS code is injected.

I see 97x errors in problematic sessions. 


Then you should open support ticket for that. Most likely the application is written in a way that including the RUM breaks it. The 97x errors are just the effect of the application itself not working.

I'd not recommend turning off the capture of 97x errors.

Certified Dynatrace Master | Alanata a.s., Slovakia, Dynatrace Master Partner

Thanks. I will.


What was the outcome of the support ticket?  I'm seeing the same issue.




Hi Antonio,
A customer started inquiring today that he has noticed these 97xx codes occasionally in their case just code 971- Canceled- The request was canceled.
Do you have experience how to work with this code and what to focus on?This code does not affect the performance of their application they are just asking how to remove the code.
In our case it is Applications created before Dynatrace version 1.238.

Thanks for response.

Hi @jiri_stefanek ,

one of the most common cases is using ad blocking in the browser or other extensions blocking the HTTP requests. The request is never sent out from the browser. You can manage the settings for these custom codes.

Certified Dynatrace Master | Alanata a.s., Slovakia, Dynatrace Master Partner

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