1) your hosting uses a piece of outdated software with the name ICU. You should ask for an update.
2) alternatively apply this fix to your shop: https://www.prestashop.com/forums/topic/1037570-backoffice-doesnt-open/?tab=comments#comment-3289539
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1) your hosting uses a piece of outdated software with the name ICU. You should ask for an update.
2) apply this fix: https://www.prestashop.com/forums/topic/1037570-backoffice-doesnt-open/?tab=comments#comment-3289539