keep getting 1909 error with all securuty turned off

Windows10. get a warning, then error, then all actions undone. Can’t even get to old version.

Please be specific. What do you mean by “all securuty turned off” - what specifically did you disabled and how?

see: Get install warning 1909 then error 2902

Turned off all I could in windows defender.

This error comes up while it appears to be trying to add a shortcut

Sigh…

Turned off all I could in windows defender.

I have no idea what you could, so still no idea what you actually did.

Specifically, you need to disable Controlled folder access in Defender’s settings for the time of installation, and subsequently re-enable and configure it to not interfere with installed LibreOffice (that later isn’t the scope of this “1909” issue though).