Adb pull - access denied I want copy all files(including system files),
but when I enter adb pull / 

i get this:

I tried entering adb root but that does nothing.


Is there any fix to this?
Else any other way to copy all files(including files like /data) to my pc?

PS:I have rooted my phone(OnePlus 6t) and have twrp and magisk.

Thanks
To (re-)enable adb root you have to modify your prop.default file. This file was traditionally named default.prop and stored inside the ramdisk of boot.img - however, for system-as-root devices it is inside /vendor.    

change the line ro.build.type=eng into:  

ro.build.type=userdebug


from the Magisk Troubleshoot Wiki:  


  ADB cannot run as root in production builds  
  
  If you're having issues running the ADB root command after installing Magisk this is because of MagiskHide setting a few prop values to known "safe" values. You can get ADB root working again by turning of MagiskHide and rebooting, but if you need MagiskHide for some app or service this could quickly become annoying.  
  
  A more convenient solution is to reset ro.build.type and ro.debuggable to their original values (userdebug and 1 respectively). This can be done by using the Magisk resetprop tool (see the Magisk Documentation for details), either by running it directly in a terminal emulator, in a late_start service boot script, or by using the MagiskHide Props Config Magisk module's "Edit MagiskHide props" function.