Drupal 8.x

I have a few requirements that I can't find an obvious way to complete with contrib modules so am looking at rolling my own.

I have a strange problem with a .theme file on a Drupal 8 (8.5.4) site

Drupal are not registrating any changes that I make to the file.
Right now the file is empty but all the old functions still active on the site.

Drupal only registrate if I rename or delete the .theme file.

I have cleared the cache with Drush cr and from the GUI, but stil no effect.

I have delete the whole theme folder at reinstalled it, but no effect.

The site is running on a nginx/1.10.3 server and using Redis Cache.

I have no knowlegs of Redis.

I'm working on a module to import a Excel file and using PhpSpreadsheet class. Now, if my uploaded file is out of public://, I have no problems at all importing it. But if I have it in public://, I get PHP message: Uncaught PHP Exception InvalidArgumentException: "File "" does not exist." at File.php line 137. Line 137 throws an exception if the file is not a file, but dpm says it is. What am I doing wrong? Below is my code:

When an images are uploaded to a Drupal 8 site, they are saved to ../sites/default/files/

I've noticed the path for images is a directory based on the Image Style name. Eg. Image Style named "teaser" will have associated images saved to ../sites/default/files/styles/teaser/public

Each Image Style does the same based on style name.

1. Is this how D8 image caching works now, or have I misconfigured something?

2. What happens to the images in these dirs if the Image Style is deleted?

[SOLVED] Was an issue on my end, please disregard.

I've modified a Content Type by adding an Image field. I do not see the image field when editing content that is currently published, but the image field is present when creating new content.

Is there a way to have the new field show-up in existing published content so that I may edit to add an image?

Unable to send email. Contact the site administrator if the problem persists.

Hi Friends, I've Faced to this error, I don't know How or where should I to adjust the SMTP settings, I can not find it on my Drupal administrator 

is this error related to my Hosting server or Cpanel??

should I install SMTP module ??

thanks in advance