• Diyan
• On February 12, 2015

Windows 10 Technical Preview for Phones is an unfinished version under development, just like Windows 10 for PCs, so you may encounter problems after upgrading. Here is a list with known issues:

Issue  – Workaround

• Existing alarms will not be migrated to Windows 10 – Reset alarms after upgrade
• Wi-Fi settings don’t roam when phone is upgraded to Windows 10 – Manually set Wi-Fi settings when on Windows 10
• VPN not available in current Windows 10 builds. Setting will fail to launch. Coming in a future update – no solution
• Additional language keyboards may not be present and may not be able to install on US builds after upgrading to Windows 10 – Reopen the Windows Insider app and re-select Insider Fast/Slow again. The download of keyboard packages will then work
• Photos app will fail to launch periodically when attempting to add a photo attachment to an email, OneNote or Facebook item – Try again. Succeeds after a few attempts.
• Quiet Hours is missing the automatic rule that enables Quiet hours during calendar appointments marked busy. Also the setting “Anyone breaks through if they call 2 times in 3 minutes” us unchecked but enabled. – no solution
• Apps are not displayed in Battery saver after the upgrade. – no solution
• Access Point Names (APNs) in recovery images can fall out of date. For some phones/networks, this will block the cellular data and MMS capabilities of a phone when recovering back to the base image. – Before using the Windows Mobile Recovery Tool to recover, record the specific APN settings on your phone.  Set manually once phone restored
• Cellular data not working while roaming, despite enabling data roaming – The setting doesn’t work the first time it’s enabled. Turning off and then turning on again will enable data while roaming
• Using a Bluetooth headset while playing back video results in low frame rate for video, due to a bug in the interaction between video playback and Bluetooth – Use wired headset for listening to audio when playing videos.
• Sync to Microsoft Band doesn’t work after updating to Windows 10. If you have your phone synced to Microsoft band, it will not pair after the update to Windows 10.- After upgrade to Windows 10, go to Bluetooth settings, un-pair the Microsoft Band device and re-pair it.
• DataSense resets data use history on upgrade to Windows 10 – No workaround. Will calculate correctly after the reset.
• Trying to set lock screen picture will fail at times – Re-attempt the operation
• After upgrade, tapping on “Playlist” from start screen or from within Music App fails to play music. Playlists are greyed out – no solution
• Cortana tile and settings are missing on the start screen after upgrade – Go to app list and re-pin the tile

Source: Windows