One reason Trulia will give the "invalid address" error code is if the property is listed elsewhere. In my case it was still listed for sale with the local MLS even though I was trying to list it for rent. *** TO OVERRIDE, you can call the Customer Service number 1 (888) 466-3501, but be prepared to wait a bit. I waited 33 minutes at 4 PM on a Monday afternoon, 2/23/15. Once they did answer, the gal named Daisy was very nice and helpful. She manually entered the address into my portfolio so all I had to do was "Edit" the listing. Interesting to note, she expressed: she too wished Trulia would provide an explanation for "invalid address" in the Help Section as it would avoid a lot of necessary questions.