Database error in log

Hi,

since some days I have an returning database error, but it seems that it has no function problems.

Doctrine\DBAL\Exception\DriverException: An exception occurred while executing ' SELECTfileid,storage,path,parent,name,mimetype,storage_mtime,mimepart,size,mtime,encrypted,etag,permissions,checksumFROMoc_filecacheWHEREstorage= ? ANDnameCOLLATE utf8mb4_general_ci LIKE ?' with params [1, "4397.v%.d1558462339"]: SQLSTATE[42000]: Syntax error or access violation: 1253 COLLATION 'utf8mb4_general_ci' is not valid for CHARACTER SET 'utf8'

Doctrine\DBAL\Exception\DriverException: An exception occurred while executing 'SELECTuid,displaynameFROMoc_usersuLEFT JOINoc_preferencespON (userid=uid) AND (appid= 'settings') AND (configkey= 'email') WHERE (uidCOLLATE utf8mb4_general_ci LIKE ?) OR (displaynameCOLLATE utf8mb4_general_ci LIKE ?) OR (configvalueCOLLATE utf8mb4_general_ci LIKE ?) ORDER BYuid_lowerASC LIMIT 500 OFFSET 500' with params ["%%", "%%", "%%"]: SQLSTATE[42000]: Syntax error or access violation: 1253 COLLATION 'utf8mb4_general_ci' is not valid for CHARACTER SET 'utf8'

What should I do? Since it is a hosting package some of my options are limited.
Any advise?

Thanks Micha