The upgrade from 181 to 2.0 doesn't work as expected on windows64 even after changing the C:\Program Files\Couchbase\Server\var\lib\couchbase\ip file. Tested with build 1967 with following steps:
1. Install 1.8.1. Create default bucket.
2. Change the hostname as per below steps:
3. Verify the hostname has been changed in the Servers section on UI.
4. Edit the C:\Program Files\Couchbase\Server\var\lib\couchbase\ip file to reflect the latest hostname.
5. Upgrade to build 1967.
6. Existing buckets prior to upgrade are not available and Servers tab shows the IP address again. The hostname change is lost.