Custom Adminhtml Grid + ORM Column Issue

Question

When creating a custom adminhtml grid, I've run into a very strange issue when modifying the column type in the database from for instance Date to varchar:

Initially - works 100% (as type Date in the table):

$this->addColumn('credit_date',
        array(
            'header'=> $this->__('Credit<br/>Date'),
            'index' => 'credit_date',
            'width' => '5%',
            'type' => 'date'
        )
    );

Updated to varchar in the table:

$this->addColumn('credit_date',
        array(
            'header'=> $this->__('Credit<br/>Date'),
            'index' => 'credit_date',
            'width' => '5%'
        )
    );

After a full re-index & cache refresh, refreshing the page now only displays the column titles and no records. I found that if I rename the column name in the table & magento, it then displays 100%.

What is the reasoning behind this strange behvaior?

Answer 1

Based on the discussion in the comments, the error appears because the grid uses saveParametersInSession set to true. The values stored in the session conflict with the database values and column names.
Solution: Log out and re login in the admin panel.