Galaxy j3 says "tab has crashed" when trying to open a webpage.

[Pah2]

The window says:

Tab Has Crashed

An error occured while displaying this webpage. To continue tap Reload or go to another page.

Nothing works on any webpage I try to open.

 

[Rukbat]

That could be that the phone is running out of RAM, because you have too many apps open. Restart the phone. In the future, when you're finished using an app, use the Back button to close it. (The Home button just runs the launcher, leaving the app running in the background.)

Each tab requires a full display buffer, so it takes a chunk of RAM.

 

[B. Diddy]

Welcome to Android Central! Try also clearing the browser's app cache in Settings>Apps​.