pagerank drop to 0 after 2-3 year(site reconstruct)

My site was located at domain without www . I check the pagerank for without www and with www, both have pagerank 3.

Then I switch my site to with www. after the while pagerank of www and without www are 0.

I set the permanent redirect and prefer domain in google webmaster correctly.

Is normal to have this drop? it is so weird since I didn't change anything. basically, just do a switch, and previously, both get pagerank 3 and now both drop to 0.

is it normal?

 

why not just change it back? Why change something that is working.

 

if you change the site content, for google, it treats you as a new site. what's more you did a switch, so i think pr has no transfer to the domain with "www" completely.

 

with all the changes in Google recently... You could've dropped PR for any number of reasons. Have you lost any search traffic?

PR is not something to be concerned about for the most part it's a distraction.

 

IF you changed the full content means then google will treat as new site and it will drop pr.

 

well, i will say this is just due to your backlink site PR drop or your backlink being removed.

 

If everything is right..... give it some time and it should be back to what you are expecting

 

I don't see why you're worrying about your PR, why not just focus on building links and quality content? Your PR doesn't decide your rankings - your content, relevancy, authority, and backlinks do.