What is error 4503?

[eburtonlab]

That number is not on this list:

https://developer.ebay.com/devzone/xml/docs/Reference/ebay/Errors/errormessages.htm

What are you doing when you encounter that error? Do you get any other error message aside from the number?

Are you on ebay.com or ebay.co.uk when you encounter it?

[hayward130453]

.co.uk and simply trying to reply to a question about an item I am listing

[eburtonlab · Accepted solution]

Try using a different link to reply to that message.

If you are replying from a selling page, use a different selling page, or go to your messages inbox.

If you have messages sent to your email, you should be able to reply directly to the email.

Try responding on ebay.com or ebay.ca rather than ebay.co.uk.

Or try responding via the app.

As a last resort, you should be able to go to the user's feedback or profile page and use the "contact" link there to compose a new message.