I open gmail and it works properly, but whenever i try reading a message it crashes. A message appears on the screen "Gmail got crashed!" (in Spanish). If i try open gmail again quickly another message appears telling: 'Gmail remains not working'.

The same issue happens with SMS app.

How cai i solve these problems?

Thanks in advance.

I highly suggest you to perform a factory reset (total wipe!) from the recovery menu, following this tutorial:
http://bbs.blackview.hk/viewtopic.php?f=192&t=334922

After the factory reset, don't load any previous phone backup, just start from scratch. This will solve your issue

Thanks for your quick answer.

I performed your suggestion, i did a factory reset.

On the first mail i have tried to read gmail has crashed, but on the second attemp i have been able to read the messages. It seems the issue has been solved.

I will try sms app on the next days.

Great support congratulations!!!!

Keep us updated!

Well, i can say definitely that the issue has been resolved succesfully. I tested SMS app, which it crashed reading messages before the factory reset was performed, and another apps with similar issues, and all have been working well right now.

Thanks for your excellent support.

Regards.

You're welcome

I had the same. 
It's because of a conflict with android webview.