Note: This release is in preview. Features described here don’t become generally available until the latest general availability date that Salesforce announces for this release. Before then, and where features are noted as beta, pilot, or developer preview, we can’t guarantee general availability within any particular time frame or at all. Make your purchase decisions only on the basis of generally available products and features.

Salesforce Classic vs. Lightning Experience Issues

These issues are caused by switching between Salesforce Classic and Lightning Experience.
Issue Solution
A UI check incorrectly returns Theme4t instead of Theme3 when the user is using the Classic UI on mobile devices. This issue occurs with Visualforce global $User.UIThemeDisplayed and Apex class UserInfo.getUiThemeDisplayed commands. Check the user’s current UI by verifying if the sforce.one JavaScript object is available; this object is not available in the Classic UI.