Over the past few builds there have been issues for users trying to install additional language packs after taking a Win10 build. We've been diligently working on the issue and have discovered the cause. Here's the details and how to work around the bug while we make the necessary changes on our side.
After updating to Windows 10 for Phone, Insiders are unable to download new language packs. Attempting to add a new language pack would show "preparing install..." and never indicate any next steps or user-required actions.
What's actually happening is that the phone is not displaying the necessary toast notification for users to check the phone update screen to download the update.
Simply put, it's a bug. Language packs are delivered to the device through the same update service that OS updates. Normally the phone would provide a toast notification at the top of the screen telling the user they have an update to install. That's not happening and as such it appears nothing ever happens on the device.
There are two ways of making this happen.
1) The easy way: Since any user taking the 10136 update will have to roll back to 8.1, the easiest method is to install any desired language packs on the device while the phone is still on 8.1 Language packs are carried forward (or reinstalled as needed) as part of the update process. They'll appear after you've completed the Win10 update.
2) The longer way: If you're on Win10 already, or if you update to Win10 and have to do a device reset (as opposed to a rollback), you can tell the device to install the update and then go to phone update and check for updates. It should then appear available for download. Detailed steps are included below:
- Launch Settings
- Tap Time & Language
- Tap Language
- Tap + Add languages
- Tap the desired language(s)
- Tap the checkmark
- Tap the back arrow and return to the Settings screen
- Tap Update & security
- Tap Phone update
- Tap Check for updates
- Follow on-screen directions as noted
***NOTE*** it may take up to 10 minutes before the update is ready to download. If it doesn't appear the first time you check, wait some time and try again.
This should download the language packs as expected. You'll need to reboot the phone for the changes to take effect. After the update is completed, you can then return to the Time & language menu in Settings and change your phone language as desired.
Until this bug is resolved, if you do a device reset while on Win10, you'll need to repeat these steps to re-download these language packs on your device.
Hope this is helpful. If you encounter any issues while trying this, please post up so we can look into it.
Thank you as always,