<Attribute android:[...] is not allowed here and t...

# stackoverflow

[user]

Attribute android:[...] is not allowed here and things
So, out of nowhere, all my .xml file started to have this error.
It told me to sync gradle, but my gradle file also have a warning but there's nothing inside.

Gradle Warning▾

I already tried the invalid caches solution , close/open the file ...
None on these worked.
PS: I can run my project without error.
Can someone help me please ?