Document upload error 'Maximum view state size limit (170KB) exceeded'

Salesforce allows Visualforce pages to have a maximum view state size of 170KB.

The View State tab shows you which elements on your page are taking up that space.

A smaller view state size generally means quicker load times.

In order to avoid this error, minimize your pages' view state. You can optimize your Apex controller code and remove any superfluous Visualforce components used.

For example:

• If you notice that a large percentage of your view state comes from objects used in controllers or controller extensions,consider refining your SOQL calls to return only data that's relevant to the Visualforce page.
• If your view state is affected by a large component tree, try reducing the number of components your page depends on.

For more information regarding the View State, review About the View State Tab