The product long description column is set to use the text datatype:
`ProductLongDesc` text NOT NULL,
the size is probably not the cause of the error.
The 500 internal server error is a very vague error that really only says "An Error Has Occurred", some servers will suppress errors from displaying and only show the vague 500 error. to get to the heart of the matter, we need to know what the real error is.
you may be able to turn error reporting on by adding the following code at line one of the product insert page:
if this does not show a more descriptive error message, you should contact your host to look into the server error logs. Once we know the real error, we can look into the cause.