src/VoyagerServiceProvider.php
protected function addStorageSymlinkAlert()
    {
        if (app('router')->current() !== null) {
            $currentRouteAction = app('router')->current()->getAction();
        } else {
            $currentRouteAction = null;
        }
        $routeName = is_array($currentRouteAction) ? Arr::get($currentRouteAction, 'as') : null;

        if ($routeName != 'voyager.dashboard') {
            return;
        }

        $storage_disk = (!empty(config('voyager.storage.disk'))) ? config('voyager.storage.disk') : 'public';

        if (request()->has('fix-missing-storage-symlink')) {
            if (file_exists(public_path('storage'))) {
                if (@readlink(public_path('storage')) == public_path('storage')) {
                    rename(public_path('storage'), 'storage_old');
                }
            }

            if (!file_exists(public_path('storage'))) {
                $this->fixMissingStorageSymlink();
            }
        } elseif ($storage_disk == 'public') {
            if (!file_exists(public_path('storage')) || @readlink(public_path('storage')) == public_path('storage')) {
                $alert = (new Alert('missing-storage-symlink', 'warning'))
                    ->title(__('voyager::error.symlink_missing_title'))
                    ->text(__('voyager::error.symlink_missing_text'))
                    ->button(__('voyager::error.symlink_missing_button'), '?fix-missing-storage-symlink=1');
                VoyagerFacade::addAlert($alert);
            }
        }
    }
protected function addStorageSymlinkAlert()
    {
        if (app('router')->current() !== null) {
            $currentRouteAction = app('router')->current()->getAction();
        } else {
            $currentRouteAction = null;
        }
        $routeName = is_array($currentRouteAction) ? Arr::get($currentRouteAction, 'as') : null;

        if ($routeName != 'voyager.dashboard') {
            return;
        }

        $storage_disk = (!empty(config('voyager.storage.disk'))) ? config('voyager.storage.disk') : 'public';

        if (request()->has('fix-missing-storage-symlink')) {
            if (file_exists(public_path('storage'))) {
                if (@readlink(public_path('storage')) == public_path('storage')) {
                    rename(public_path('storage'), 'storage_old');
                }
            }

            if (!file_exists(public_path('storage'))) {
                $this->fixMissingStorageSymlink();
            }
        } elseif ($storage_disk == 'public') {
            if (!file_exists(public_path('storage')) || @readlink(public_path('storage')) == public_path('storage')) {
                $alert = (new Alert('missing-storage-symlink', 'warning'))
                    ->title(__('voyager::error.symlink_missing_title'))
                    ->text(__('voyager::error.symlink_missing_text'))
                    ->button(__('voyager::error.symlink_missing_button'), '?fix-missing-storage-symlink=1');
                VoyagerFacade::addAlert($alert);
            }
        }
    }
Add storage symlink alert.