Recent Windows update causes IP configuration error:
 
The following from a command prompt may solve the issue
 
netsh winsock reset
netsh int ipv4 reset
 
Some instances have required a callout. The common factor seems to be mainly BT routers.
 
Various issues causing problems at the point of upgrade have been encountered.
 
These can usually be avoided by ensuring your PC is free from infection BEFORE attemting to upgrade.
 
Ensuring all updates are done (including optional ones) is also recommended. Check the maufacturer's site for Driver and BIOS updates. There are some
occasions where certain programs and Apps have prevented Windows 10 from installing correctly.
 
Please also ensure that all of your language settings are correct as this may also cause problems at the point of upgrade. If you encounter issues with Cortana not being available it is usually for this reason.
 
If you find you have US English as your default it is usually because your language settings were not consistent before upgrading. Do not despair, you need not reverse the upgrade, BUT you should ensure UK English (and all  UK Speech, UK Text and UK Language packs) are downloaded BEFORE changing your default language (and speech) to UK English. Once this is done reboot before removing the US language.
 
Possible hard drive corruption should be checked for using these steps:
 
Opening an administrator command prompt and running "sfc /scannow" command followed by a restart.
 
Then if there are errors that could not be fixed:
 dism /online /cleanup-image /scanhealth
 dism /online /cleanup-image /checkhealth
 dism /online /cleanup-image /restorehealth
 
You can also use a version of these commands with a DVD (of Windows 10) to repair using that image rather than online.
 
 
 
Early Windows 10 upgrade issues: (most of these were cured after the November 2015 build.)
 
Where an account was not linked to a Microsoft account before the upgrade it may cause corruption linking to a Microsoft account other than by using the new Cortana feature. This results in the new Edge browser closing itself instantly and the windows desktop flickering madly.
 
This  was corrected by creating a new user profile and migrating all of the user data to the new account was it had been linked to a Microsoft account with Cortana.
 
 
 
Microsoft Outlook 2010 (although we have read that other versions are also affected) unable to send emails after the upgrade. Recreating Outlook profile and removing and adding email account did not work.
 
Sending’ reported error (0x800CCC13): ‘Cannot connect to the network. Verify your network connection or modem’
 
This was fixed by opening an administrator command prompt and running "sfc /scannow" command followed by a restart.