What this transform_entities() error means

error
transform_entities
entities
transform
transformation

#1

I tried to apply transformation method to array of entities and got this error
#<ArgumentError: All Entities must have a common parent>


#2

Please repost your error message, preceding and following it with lines containing three backtick characters ( ` not apostrophe or single quote). That will prevent the forum software from trying to process your message as markdown and therefore “disappearing” anything surrounded by angle brackets.