Recently, many Insiders have reported that when attempting to update to the latest Windows 10 build on Lumia phone (especially Lumia 650), they got the problem with the error code 0x80188308. We have noticed that it’s a known issue but you still have some choices to fix it.
Easy ways to bypass the Error 0x80188308
1. Try upgrading your Lumia phone without a SD card, this may help on some devices.
2. Do a hard reset without installing any apps, this will let the Windows to fix itself
Stable solution for this error
Just set your phone to the slow ring for Insider and wait for the new path.
I hope that this information will be helpful for you. If you have any concern or you know another way to fix the problem, please comment below.