KI-158

Field Audit Trail Download button fails in Salesforce Winter '27

Created date	09/30/2026	Updated date	09/30/2026
Status	In Progress	Related work item	PLTFM-3720
Description	In orgs on Salesforce Winter '27 with Lightning Web Security (LWS) enabled, clicking Download on the Field Audit Trail (mvn:atFieldAuditTrail) Related List component doesn't generate a CSV file. Instead, the following error appears: Lightning Web Security: HTMLAnchorElement href does not support data:, javascript: or vbscript: schemes. This affects only the CSV download. The component still displays audit trail records as expected.
Root Cause	In Winter '27, Salesforce blocks a code pattern it previously recommended for downloading dynamically generated files. Code that followed the earlier best practice no longer works. For details, see HTMLAnchorElement href No Longer Supports data:, javascript:, or vbscript: Schemes. This issue affects every org upgraded to Winter '27.
Affects version(s)	Fall '26 Minor Release 1 and older	Impacted capabilities	Audit Trail
Steps to reproduce	In an org on Salesforce Winter '27 with LWS enabled, open a record whose Lightning record page includes the Field Audit Trail Related List component. In the Field Audit Trail Related List, click Download. Observe that the LWS error appears and no file downloads.
Workaround	There's no in-app workaround. The audit data isn't affected. Until you install the fix, export audit records with a data tool such as Data Loader or Workbench instead of using the Download button.
Fix version	Hotfix 2	Resolution notes	The Download button now builds the CSV file with a blob object URL, which LWS allows, instead of a data: URL. The fix is included in the upcoming Hotfix 2.