@WarBuddha said in Can't enable SessionRestore on Safari 13.1:

I am sorry. It is not your app fault, because all extensions box are not able to tick.

Is this happening while you're using macOS Catalina? If so, it's a known bug in Safari, apparently introduced in Catalina v10.15.3, which has been very thoroughly documented by solo developer Jeff Johnson, and mentioned by many others, including Michael Tsai and Rob Griffiths. As far I'm aware, the bug has still not been fixed as of Sept 2020. In late July, Apple did at least acknowledge the problem by posting a brief support article that merely suggests rebooting your Mac in "safe mode" in order to enable your Safari extensions, then rebooting normally.