Hello.

This error usually happens if you used an add-on to create a table, for example if you had an integration with a Form Plugin;

 or if you previously had our Premium Version of wpDataTables which has some additional table types that are not available in free/Lite Version, and then if you removed or deactivated that add-on on your site;

 or if you somehow downgraded from Premium to Lite, and have a table which is not available in Lite - then you would get this error. 

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1. I recommend to first check if you might have somehow 'downgraded' from Premium wpDataTables to Lite :

If you don't see the Activation Tab in the main plugin settings, it means that you have the Lite plugin version installed.

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Please follow the steps explained here, 

it is a step-by-step explanation of how you can safely remove the Lite version and install + activate the Full version.

2. If you already have the Full latest version 6.2.1 installed;

check what is the Table type and did you use an Add-on on this table?

For example, if you used Master-Details feature, and if the Master-Details add-on somehow got disabled on your Site;

Please check do you have the latest Add-on version installed.

You can check all the latest version numbers on this ChangeLog Page, just change between the tabs on top to see it for Add-ons, too.

If an auto-update is not offered, and you see you got an old version;

The same process for Add-ons is as if you update a Plugin.

You can see our Guide here : Updating the plugin to the latest version.

Let me know if that helps.