BuddyPress.org

Do you mind doing a little debugging for me? If you paste the following code into your theme’s functions.php file (make sure this is done on your testing install). Then visit the activity stream. You should see some output dumped on the screen. Can you copy that and paste it here?

add_filter( 'bp_after_has_activities_parse_args', function( $retval ) {
    var_dump( $retval['action'] );
    return $retval;
} );

It is an html error in some code in your installation that first checks to see if the user is logged in.
You’ll have to search through your theme files for this text: Νέο,Θέμα
And correct the error.

If you cannot find it in your theme, it may be coming from a plugin.

Is your edited file in the correct place?
It should be here:
.../wp-content/themes/your-theme/buddypress/groups/create.php

Create a template overload of this file:
buddypress\bp-templates\bp-legacy\buddypress\groups\create.php

Then, in your template overload, remove the html for the Private and Hidden options.

This will turn off registrations altogether, thus removing the BuddyPress missing page nag:

Go to your WordPress’ Settings > General page and uncheck Membership Anyone can register

Don’t know how that will effect your theme’s registration, though…

google “micro job wordpress theme” and would give you couple of paid options

install theme my login plugin and then you can use “login” page

check with Divi Theme author…check if Divi Theme defines a custom register page

@osamanuman @danbp told you to check with Twenty Fifteen and update this thread…instead of that you say “contact with my theme developer”..if its a custom theme your theme developer can fix it..the issue is not related to buddypress…

have you checked this before starting off: https://codex.buddypress.org/getting-started/

PHP must have the GD or imagick modules installed (on the server) to allow re-sizing of images; BP avatar uploads will fail without one of these modules activated (WP will simply fail to create image sizes for posts but won’t show an error)

this might help….create index-register.php

Template Hierarchy

Have you tried asking the creators of the Sahifa WP theme?

You can put it in your theme/functions.php or in bp-custom.php.