Web service fail to access but Tomcat is still "Started"

I am using Apache Tomcat 8, MSSQL, window server 2008 R2 to implement my web page.

The web page service is normal most of the time. It cannot be accessed unexpectedly.

When the web page service cannot be accessed, the Service Status in Tomcat panel shows "Started".

The web page service will resume normal after I restart Tomcat.

28-Jan-2019 22:36:26.762 SEVERE [http-nio-9191-exec-61] 
com.microsoft.sqlserver.jdbc.TDSReader.throwInvalidTDS TDSReader@6c8543c5 ( 
ConnectionID:3622 TransactionID:0x0000000000000000) got unexpected value in       
TDS response at offset:157

28-Jan-2019 22:37:45.434 SEVERE [http-nio-9191-exec-60]             
com.microsoft.sqlserver.jdbc.TDSParser.throwUnexpectedTokenException 
TDSReader@c6cc18b ( ConnectionID:3631 TransactionID:0x0000000000000000): 
FetchBufferTokenHandler: Encountered unexpected TDS_RETURN_VALUE (0xAC)

28-Jan-2019 22:37:45.434 SEVERE [http-nio-9191-exec-60] 
com.microsoft.sqlserver.jdbc.TDSReader.throwInvalidTDS TDSReader@c6cc18b ( 
ConnectionID:3631 TransactionID:0x0000000000000000) got unexpected value in 
TDS response at offset:157

28-Jan-2019 23:40:28.340 SEVERE [http-nio-9191-exec-79] 
com.microsoft.sqlserver.jdbc.TDSParser.throwUnexpectedTokenException 
TDSReader@649469de ( ConnectionID:3655 TransactionID:0x0000000000000000): 
closeServerCursor: Encountered unexpected TDS_COLMETADATA (0x81)

28-Jan-2019 23:40:29.512 SEVERE [http-nio-9191-exec-79] 
com.microsoft.sqlserver.jdbc.TDSReader.throwInvalidTDS TDSReader@649469de ( 
ConnectionID:3655 TransactionID:0x0000000000000000) got unexpected value in 
TDS response at offset:0

After the above log in Tomcat appears, the web page cannot be accessed anymore until Tomcat is restarted.

How to keep the web page running normally?