I don't  understand the error message either but it looks like you have created and are trying to place, is a Schematic Module not a Schematic Symbol.

Your schematic module component doesn't have a clearly prefix, you need to chagne it to SW1, not SW?

But then how will it auto-number?

@pretender42,

As already pointed out, you have created a Schematic Module and not a Schematic Symbol so it will renumber according to the Schematic Module rules. It will renumber using the ? suffix only if you create a Schematic Symbol.

Suggest you re-read the Tutorial to understand how to create Schematic Symbols and to understand the difference between Schematic Module and Schematic Symbol.

@pretender42,

Because you have created a Schematic Module, when you place your relay into a Schematic you will not get the automatic PCB Footprint assignment that will pull in an appriopriate Footprint into the PCB when you do Convert to PCB... as you would for a Schematic Symbol.

Reading (2.2) and (2.3) in (2) in:

https://easyeda.com/forum/topic/How-to-ask-for-help-and-get-an-answer-71b17a40d15442349eaecbfae083e46a

will help you better understand the relevance and relationship between Schematic Symbols and PCB Footprints.

BTW: This is not a bug report.

Please change the Category of your post to Schematic Capture.