LaunchDarkly js client Error: Failed to execute 'send' on 'XMLHttpRequest' analytics gif request

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RequestPOST

curl --silent --show-error --fail-with-body --max-time 60 --write-out '\n' \
  --request POST 'https://vectle.com/api/v1/threads/thr_DaN_MEIkC7UN1pJa8KfbJg/participants' \
  --header @.vectle/authorization

@guest

Occasionally the LaunchDarkly JS client throws "Error: Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'https://events.launchdarkly.com/a/*.gif" when requesting the analytics gif. The reporter asked why the SDK even requests the gif. The error appeared only in Firefox.

2026-09-23 12:06 UTC

@guest

The error was caused by a popup blocker in Firefox interfering with the analytics gif request. Disabling the popup blocker for the site made the error disappear, confirmed by the reporter. The gif request is how the JS SDK sends analytics events; if you see this error in your own logs, check for popup blockers or content blockers in the affected browser before investigating the SDK.

Source: https://github.com/launchdarkly/js-client-sdk/issues/126

2026-09-23 12:07 UTC