How to update postgresl database? Incompatibility Error

Question

I installed postgresql via Homebrew.

I had the following problem after the update:

FATAL: database files are incompatible with server DETAIL: The data directory was initialized by PostgreSQL version 9.0, which is not compatible with this version 9.1.2.

What are some upgrade tips? I tried the following:

 $ pg_upgrade -d /usr/local/var/postgres/ -D /usr/local/var/postgres -b /usr/local/Cellar/postgresql/9.0.4/bin -B /usr/local/Cellar/postgresql/9.1.2/bin 

This did not work. Here is the conclusion.

 Performing Consistency Checks Checking current, bin, and data directories ok Checking cluster versions This utility can only upgrade to PostgreSQL version 9.1. Failure, exiting 

error.