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RUM dtSa cookie > 4096 bytes ?

DynaMight Guru
DynaMight Guru

The Dynatrace dtSa RUM cookie encodes the <URL-encoded action name>:


An URL can be longer than 4096 bytes, or even much longer. RFCs stipulate that user-agents should support cookies that are at least 4096 bytes long, and Chrome supports just that:


So, what happens when the URL of a page is bigger than that, in Dynatrace RUM, in the dtSa cookie?

Antonio Sousa

DynaMight Legend
DynaMight Legend

@AntonioSousa did you get an answer to this question? If so would you mind sharing it with the community? 


DynaMight Guru
DynaMight Guru


No, I didn't get an answer, and also didn't have the chance to test.

Antonio Sousa



we are getting a 431 http error Request Header Fields Too Large on some monitored applications.

we are suspecting the dtsa cookie to be the root cause. the size of the cookie exceeds 1024 bytes.

how can we be sure that this is the root cause?

is there a way to truncate that cookie? what are the possible impacts on monitoring?



Please create ticket to the support, it exists some special attributes which could be applied into custom configuration for Javascript tag properties.  Namely, we have possibility to shorten the length of this cookie.
Afterward, you will have 3 options : 
- store the dtSa into sessionstorage if supported 
-  disable it completely
- or change reverse proxy , if it is apache look into configuration in order to increase header size for instance.

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