If you have the Wi-Fi calling (TMO) feature in use in your phone, please clear the temporary files with the Storage Check app when the Wi-Fi is turned off. This will vacate more space.
- Update the Storage Check app (to version 18.104.22.168 or higher, when available).
- Set Wi-Fi off (Settings > WLAN > Toggle off).
- Launch Storage Check.
- Press the Clear button to delete the files.
- Update your Lumia to Black.
Note: You may also have too little space on the user disk. Please move some content to the cloud or other storage to vacate more space.