Office 365 Nintex Forms "Input string not in the correct format"
When attempting to open a list item with a Nintex form published, the form errors with - "Input string not in the correct format".
Open the Nintex Forms designer
Export and save a copy of this form
Delete the form
Import the form through the designer and publishing.
"Input string not in the correct format"
If this error is occurring via a Nintex Workflow, please check your Nintex Forms that are configured in the Nintex Workflow actions, such as "Assign a Task", and any Nintex Forms published to any content type on affiliated lists (including task lists) or libraries.
If step 1 doesn't work because the forms designer cannot be opened, see related links.