Dr.Wily

OK, thank. I will contact my host to found what the problem is.

so, just to clarify in case there was any confusion: you successfully rolled back to The Events Calendar 4.7.4, and have it activated

No I try this with the last version. With 4.7.4 it works. Here the system information :

Home URL
    https://www.asso-sc.com
Site URL
    https://www.asso-sc.com
Site Language
    fr_FR
Character Set
    UTF-8

Install keys
    -
WordPress version
    5.0.3
Permalink Structure
    https://www.asso-sc.com/%postname%/
PHP version
    5.4.45
PHP

        max_execution_time = 300
        memory_limit = 512M
        upload_max_filesize = 128M
        post_max_size = 130M
        display_errors = 0
        log_errors =

Server
    Apache
SAPI
    fpm-fcgi
Plugins

        Akismet Anti-Spam version 4.1.1 by Automattic(https://automattic.com/wordpress-plugins/)
        Change WP Mail From Details version 1.0 by Ruhul Amin(http://www.tipsandtricks-hq.com)
        Convert Post Types version 1.4 by Stephanie Leary(http://stephanieleary.com)
        Facebook Page Plugin (Likebox) version 1.7 by Smakify(http://smakify.com)
        Fancy Gallery Lite version 1.5.37 by Dennis Hoppe(http://DennisHoppe.de)
        Flexo Archives Hack MOD version 2.1.5 b0.1 by Heath Harrelson
        Image Widget version 4.4.7 by Modern Tribe, Inc.(http://m.tri.be/iwpdoc)
        Juiz Social Post Sharer version 1.4.9 by Geoffrey Crofte(http://geoffrey.crofte.fr)
        Fast Secure Contact Form version 4.0.56 by fastsecure(http://www.642weather.com/weather/scripts.php)
        Social version 3.1.1 by Crowd Favorite(http://crowdfavorite.com/)
        Stop Spammers version 7.1 by Bryan Hadaway(https://calmestghost.com/)
        The Events Calendar version 4.7.4 by Modern Tribe, Inc.(http://m.tri.be/1x)
        Update Notifications Manager version 1.1.2 by GeekPress(http://www.geekpress.fr/)
        Widget_custom version 1.0 by DtrAA(http://david.desaunais.fr)
        Wordfence Security version 7.2.2 by Wordfence(http://www.wordfence.com/)
        WP-Filebase version 0.2.9.35 by Fabian Schlieper(http://wpfilebase.com/)
        WP User Avatar version 2.1.6 by flippercode(http://www.flippercode.com/)
        WS Facebook Like Box Widget version 4.1 by WebShouters(http://www.webshouters.com/)

Network Plugins
    -
MU Plugins
    -
Theme
    Simm's Club
Multisite
    -
Settings

        tribeEventsTemplate = page-calendar.php
        tribeEventsBeforeHTML =
        tribeEventsAfterHTML =
        previous_ecp_versions =

        Array
        (
            [0] => 0
            [1] => 2.0.11
            [2] => 3.12.3
            [3] => 4.0.7
            [4] => 4.1.2
            [5] => 4.4.2
            [6] => 4.6.8
            [7] => 4.6.25
        )

        latest_ecp_version = 4.7.4
        welcome_notice = 1
        displayedPressTrendsDialogue = 1
        donate-link =
        viewOption = month
        eventsSlug = events
        singleEventSlug = event
        postsPerPage = 3
        showComments =
        multiDayCutoff = 12:00
        embedGoogleMaps = 1
        embedGoogleMapsHeight = 350
        embedGoogleMapsWidth = 100%
        embedGoogleMapsZoom = 10
        sendPressTrendsData =
        debugEvents =
        tribeEnableViews =

        Array
        (
            [0] => list
            [1] => month
            [2] => day
        )

        schema-version = 4.7.4
        recurring_events_are_hidden = hidden
        earliest_date = 2013-04-18 08:00:00
        latest_date = 2019-01-12 08:00:00
        earliest_date_markers =

        Array
        (
            [0] => 380
        )

        latest_date_markers =

        Array
        (
            [0] => 1682
        )

        last-update-message-the-events-calendar = 4.7.4

WP Timezone
    Europe/Paris
WP GMT Offset
    1
Default PHP Timezone
    UTC
WP Date Format
    j F Y
WP Time Format
    G \h i \m\i\n
Week Starts On
    1
Common Library Dir
    /home/assosc/www/wp-content/plugins/the-events-calendar/common/src/Tribe
Common Library Version
    4.8.5