What does the “Invalid block type” exception mean?
This exception usually means that your layout files are referencing a block that does not exist. This could be because an extension was disabled / deleted or because there is a typo in one of the layout files.
How do I solve this type of issue?
Look at the block name and search your layouts for any reference to this block. You can then either remove the layout reference or create the block it is referencing.
We understand that sometimes there simply is not a pre-made extension that meets your specific needs. In these instances you need custom development. In addition, custom development can help squash bugs, debug 3rd party extensions, optimize your store, provide consultation, and more.