error: Error parsing XML: not well-formed (invalid token) …?

Question

I am working on an application, with following XML. but whenI try to clean/build my project the following error occurs:

\"error: Error parsing XML: not well-formed (

Answer 1

Remove the semicolon after hello

Answer 2

I had this problem, and when I had android:text="< Go back" it had the correct syntax highlighting, but then I realized it's the < symbol that is messing everything up.

Answer 3

In my case I forgot to end my ConstrainLayout

</android.support.constraint.ConstraintLayout>

After that, everything started working correctly.