41. Common errors

1.persistence.xml: 

a. Verify that all the entities are defined inside a persistence unit 

<class>openadmin.model.gexflow.original.territori.CllCodigoPostal</class>
<class>openadmin.model.gexflow.original.territori.CllComarca</class>
<class>openadmin.model.gexflow.original.territori.CllHueco</class>

b. and also that no other classes are allowed

<exclude-unlisted-classes>true</exclude-unlisted-classes>

c. Verify that the same class (<class>myclass</class>) is not defined in 2 or more persistence units or in case it is duplicated, you must only use one persistence unit in your program

d. Verify which databases are only for query (and not updatable) and use the value "none" to schema modification

<property name="hibernate.hbm2ddl.auto" value="none" /> <!--NO SCHEMA MODIFICATION -->
<property name="hibernate.hbm2ddl.auto" value="update" /> <!--sCHEMA MODIFICATION !!!! -->

2. DB Server corruption

a. Symptoms: After a power failure, when a schema in a Postgres database is accessed from different web servers, one of the servers can fill the schema with "YAMLControlLoad" and cannot see the content of the schema, and the other one can see the content of the schema.

Maybe it is a caché problem or database corruption. If you have a backup, then drop the database and recreate it, and load the backup.

3. Tomcat fails

a. Symptons: Very slow tomcat startup and sometimes fails to deploy heavy applications

1.Save the WAR to deploy from the webapp folder

2. Delete the tomcat directory

3. Download a copy of the apache-tomcat.zip and reinstall it

4. Restore the WAR file into the webapp folder

5. Edit the conf/tomcat-users.xml as seen in Dantesque-Vaadin for allowing the user tomcat and roles tomcat and manager-gui

6. Edit wepapps/manager/META-IONF/context.xml for allowing access to other computers as seen in Dantesque-Vaadin

7. Execute bin/.startup.sh and try if has deloyed the application.