Have you added any language files, i.e. any additional languages apart the English language files that are bundled with Elgg core, or have you modified any language files? If yes, it's possible that any of these additional/modified language files is saved with wrong encoding resulting in issues. If you have added or modified any language files save them with encoding "UTF-8 without BOM". This would correct at least the encoding. But no promise that this is connected with your issue.

@iionly we added another language and edited the original, but I see that all of them are well encoded! don't seems to be that problem. I will try anyway to put the original languages files to see if it gets solved, thank you anyway!

The page is still creating, so I'm thinking to reinstall it to try to solve the problem. I activated the PHP error log but still giving the white page, is strange.

Finally I reinstalled the site and now is all working, thanks to @iionly and @Team Webgalli anyway for the help!!