Root D6603 on .77 by downgrade, no data wipe topic

I managed to use giefroot root my D6603 (US version) on firmware 23.0.1.A.5.77 by downgrading to 23.0.A.2.93 without wiping the whole /data.

This is what I did: (Try at your own risk!)
1 Backup the contacts first. The contacts data will be cleared.
2 Use Flashtool to flash D6603_23.0.A.2.93_Generic_20GLOBAL.ftf. Uncheck wipe DATA.
3 Restart the device. There will be lots of annoying force close popups. For me, only two packages were reported closing: android.process.acore and android.process.media. USB debugging doesn’t work either.
4. Just close the popups and go to Settings – Apps – All. Find “Media Storage” and press “clear data” to get rid of FCs of android.process.media. USB debugging should work now.
5. Find “Contacts Storage” and press “clear data”. No more FCs of android.process.acore.
After this, no more FC popups for me. It looked normal on fw 2.93 and I tried many times to use giefroot v2 but failed. It seems like that the system exploit app CVE-2014-7911 will crash android.
6. I tried clearing data of more apps. After clearing ApplicationSettings and ConfigUpdater, giefroot v2 worked! I don’t know which one is the key. Can anyone confirm?

Hope it's helpful for you.

Thanks again! @zxz0O0