I am Getting the error Call to undefined method Mage_Catalog_Helper_Product_Compare::setCustomerId() After Upgrading From Magento 1.4 to 1.9.1
Any help will be appreciated.
boussema and welcome to MageOverflwo. This is unfortunately FAR to less information. You should at least provide a stacktrace.
But in 1.9.1 the method exists, so maybe you didn't upgrade all files?