Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException
Solution 1
There is CommunicationsException: Communications link failure.
If you get a SQLException: Connection refused or Connection timed out or a MySQL specific
CommunicationsException: Communications link failure
then it means that the DB isn't reachable at all. This can have one or more of the following causes:
- IP address or hostname in JDBC URL is wrong.
- Hostname in JDBC URL is not recognized by local DNS server.
- Port number is missing or wrong in JDBC URL.
- DB server is down.
- DB server doesn't accept TCP/IP connections.
- DB server has run out of connections.
- Something in between Java and DB is blocking connections, e.g. a firewall or proxy.
To solve the one or the other, follow the following advices:
- Verify and test them with ping.
- Refresh DNS or use IP address in JDBC URL instead.
- Verify it based on my.cnf of MySQL DB.
- Start the DB.
- Verify if mysqld is started without the --skip-networking option.
- Restart the DB and fix your code accordingly that it closes connections in finally.
- Disable firewall and/or configure firewall/proxy to allow/forward the port.
Source: More Details
Solution 2
DB is down. You must start the DB server and check connectivity with either telnet or mysql command line client first.
emoleumassi
Updated on July 31, 2022Comments
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emoleumassi over 1 year
when i run my code, i get this exception:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:422) at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121) at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:357) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2482) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2519) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2304) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:422) at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:346) at java.sql.DriverManager.getConnection(DriverManager.java:664) at java.sql.DriverManager.getConnection(DriverManager.java:208) at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:153) at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriver(DriverManagerDataSource.java:144) at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnectionFromDriver(AbstractDriverBasedDataSource.java:155) at org.springframework.jdbc.datasource.AbstractDriverBasedDataSource.getConnection(AbstractDriverBasedDataSource.java:120) at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:139) at org.hibernate.tool.hbm2ddl.SuppliedConnectionProviderConnectionHelper.prepare(SuppliedConnectionProviderConnectionHelper.java:51) at org.hibernate.tool.hbm2ddl.DatabaseExporter.<init>(DatabaseExporter.java:52) at org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:367) at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:304) at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:293) at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:517) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1857) The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. Aug 25, 2015 8:23:45 PM com.sun.jersey.spi.container.ContainerResponse mapMappableContainerException SCHWERWIEGEND: The RuntimeException could not be mapped to a response, re-throwing to the HTTP container org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; nested exception is javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Could not open connection at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:431) at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373) at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:457) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:276) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207) at com.sun.proxy.$Proxy76.create(Unknown Source)
I don't know where is the problem. But yesterday i worked fine.
my database.properties:
jdbc.driverClassName=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/streaming jdbc.username=root jdbc.password=password hibernate.dialect=org.hibernate.dialect.MySQLDialect hibernate.showsql=true hibernate.hbm2ddl.auto=create
It is possible for me to run mysql directly from command line. Where is the problem? Was is wrong. I use spring 4 and hibernate with mysql as database language.
Has someone any ideas?
Thank.
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Amit Tamrakar about 8 yearscheck the DB server status. Is it working.
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chabeee over 7 yearsDo you use JPA.em("default") ?
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emoleumassi about 8 yearsi can run succefully mysql -u root -p on the console. DB down. But when i run with sudo /usr/local/mysql/support-files/mysql.server start Starting MySQL .................................................................................................... i get this: ERROR! The server quit without updating PID file (/usr/local/mysql/data/Me-MBP.local.pid).
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ACV about 8 yearswhat linux are you using. Try sudo service mysqld start
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ACV about 8 years
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ACV about 8 yearscan't think of anything but ps aux | grep mysqld then if exists, sudo kill -9 pid, check firewall, restart.
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emoleumassi about 8 yearsThank but i don't time enough time. I decided to reinstall mysql and it is working fine now.
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ACV about 8 yearsStrange, could be due to that pid file staling there
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emoleumassi about 8 yearshummmm. When i start my mac and run the mysql server i get the same error. What is wrong?
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ACV about 8 yearshow do you start mysql server?
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emoleumassi about 8 yearsyes, but same error, see stackoverflow.com/questions/32234142/…
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Piyush about 6 yearsI am running a Spring Boot Microservice with MariaDB database, where I am facing the same issue. None of the above reasons hold true in my case. The service is able to connect to the db for a few hours and then I start seeing this connection error. When I restart the service, the issue is resolved again. It appears that the connection pool runs out of valid connections. I have played around with spring.datasource.tomcat.* properties (testOnBorrow:true, validateQuery: SELECT 1, testWhileIdle: true, timeBetweenEvictionRunsMillis: 1000, logAbandoned: true), but that has not helped.