Live Preview Button missing I upgraded to Craft 2.1 and there is no Preview Button visible. 

It must have something to do with the configuration I created for the different sections because when I use the same craft installation with a clean database the preview button is visible.
For the Live Preview button to show up, two criteria must be met:


Your section’s “Entries in this section have their own URLs” setting must be checked
Your section’s “Entry Template” setting must be set to a valid template path
For Craft 3.2+ pro version, a preview target must be specified. This happens automatically, but might be missing due to a bug. Add a preview target with Primary entry page => {url} to fix this.


Make sure both of those are set correctly, and the Live Preview button will show up.