MysqlException: max pool size was reached.

2019-09-09 08:22:08.620 +00:00 [ERR] Connection id "0HLPKVK52H2OU", Request id "0HLPKVK52H2OU:00000001": An unhandled exception was thrown by the application.
MySql.Data.MySqlClient.MySqlException (0x80004005): error connecting: Timeout expired.  
The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached.
   at MySql.Data.MySqlClient.MySqlPool.GetConnection()
   at MySql.Data.MySqlClient.MySqlConnection.Open()
   at System.Data.Common.DbConnection.OpenAsync(CancellationToken cancellationToken)
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