Probably worth its own thread, but a couple of points
- There is a problem with the 0.21-r build reported in this thread. It has been fixed, but the fix won’t be available until the v0.22 build. If you need your hotpsot to work, then don’t flash the v0.21-r buiild.
- I’m not sure where those notes come from - I don’t recall writing them
. - This post describes the steps I have used to successfully ‘dirty flash’ R ROMs over an existing Q installation: Week 36 : Development and Testing Updates - #11 by tcecyk
- If the dirty flash doesn;t work, then you should format - not just wipe - the data partition in TWRP before flashing the R ROM. Then reboot the device and go through the first time setup, before restoring teh data backup and following steps 2 and 3 in the linked post
- I have never tried the process of upgrading Q → R and going to the next /e/OS version (i.e. 18-q to 21-r). My testing involves upgrading Q → R with the same /e/OS version (i.e. 21-q to 21-r). It shouldn’t make a difference, but I would always update tp the latest /e/ version before upgrading
- The problem in that thread is (almost certainly) a completely different problem, even though the symptoms may be the same
@Manoj We will need to do something about the misleading and wrong ’ /e/ OS Version Upgrade’ documentation for suzuran and z3c. I don’t recall reviewing them, and they contain some pretty serious errors and omissions 
Please can you add a warning to those pages that they are not reliable, and following them may cause problems with the upgrade?