Hi all,
A few hours ago I finally managed to update my Nokia Lumia 820 with WP8.1 GDR1. Before I was getting the error code 0x80188308, and I had WP8.1 Developer Preview + Lumia Black.
What I did is as follows:
I formatted the SD card. - It did not help. Phone memory (not the SD card) available: 3.1 GB
I reset my device + formatting the SD card at the same time. Then restored the same Microsoft account with the backup, and before redownloading all the apps, I downloaded only the Preview for Developers app, logged in again, and downloaded the update with English (UK) settings everywhere. - It worked!
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Other details about my phone: Still having Lumia Black, product code for Germany, Available phone memory: 4.5 GB.
This is what I did - I hope it would help some of you. Keeping my fingers crossed!