From the exception you've got there, it looks like your Visualforce page has been impacted by previous encryption you've made. Although you've disabled the encryption on Contact.Name/Account.Name - which is a composite field, i.e., comprised of FirstName and LastName - the underlying encrypted values are not reverted back to plain text automatically.
In this case, try to open the record via vanilla page layout (if possible) and update a particular record or retrieve the Id, First Name, and Last Name via Data Loader so you'd retrieve them in plain text, then mass-update them again via Data Loader so this time they'd be persisted in plain text. Then your VFP should work again.
Alternative solution is to keep the Contact.Name / Account.Name encrypted but update your SOQL such that it complies with the restrictions by using formula/functions that are supported by Shield. Check out the latest version of Shield's implementation guide