https://dc.services.visualstudio.com/v2/track returning 400 bad request in case of log out about applicationinsights-js

[MSNev]

We released v3.0.6 to npm yesterday to address an issue introduce in v3.0.4 which causes this issue to occur.
And we promoting v3.0.6 as the primary version (available via the CDN with ai.3.min.js and ai.3.gbl.min.js) on Monday

v3.0.6 is a targeted fix for this specific issue https://github.com/microsoft/ApplicationInsights-JS/milestone/90

[MSNev]

For reference, this issue is triggered only when the browser is unable to send all events that are "batched" (in-memory) when the page is "unloading" (Navigating to another page, closing the browser or switching to another tab).

This generally, means that the "amount" of batched events exceeds the sendBeacon() limit of 64Kb. The ping means that the request is being attempted via the sendBeacon API.

[MSNev]

Not sure exactly "why" it's returning a 400 though, perhaps because too many events have being "sent".

Can you try using v3.0.6?

• If you using npm then just consume the latest package.
• If your using the CDN (snippet) then you can change the src to be ai.3.0.6.gbl.min.js or ai.3.0.6.min.js (at least until Monday (PST) when we promote this version to be the primary version.