Activiti database problem: Tables missing for component (s) engine error pit to solve!-CodePudding

Environment: springboot2.1.2 + activiti6.0
Create a new project, introducing the activiti, what all not dry enough, for the first time the runtime creates 28 activiti table, the second time the runtime is submitted to the following error, too strange!
Reference

org. Activiti. Engine. ActivitiException: activiti database problem: Tables missing for component (s) engine
The at org. Activiti. Engine. Impl. Db. DbSqlSession. DbSchemaCheckVersion (DbSqlSession. Java: 814) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Engine. Impl. Db. DbSqlSession. PerformSchemaOperationsProcessEngineBuild (DbSqlSession. Java: 1315) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Engine. Impl. SchemaOperationsProcessEngineBuild. Execute (28) SchemaOperationsProcessEngineBuild. Java: ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
At org.activiti.engine.impl.interceptor.Com mandInvoker $1. The run (CommandInvoker. Java: 37) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
At org.activiti.engine.impl.interceptor.Com mandInvoker. ExecuteOperation (CommandInvoker. Java: 78) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
At org.activiti.engine.impl.interceptor.Com mandInvoker. ExecuteOperations (CommandInvoker. Java: 57) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
At org.activiti.engine.impl.interceptor.Com mandInvoker. Execute (CommandInvoker. Java: 42) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Engine. Impl. Interceptor. TransactionContextInterceptor. Execute (TransactionContextInterceptor. Java: 48) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
At org.activiti.engine.impl.interceptor.Com mandContextInterceptor. Execute (CommandContextInterceptor. Java: 63) ~ [activiti - engine - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Spring. SpringTransactionInterceptor $1. DoInTransaction (SpringTransactionInterceptor. Java: 47) [activiti - spring - 6.0.0. Jar: 6.0.0]
The at org. Springframework. Transaction. Support. TransactionTemplate. Execute (TransactionTemplate. Java: 140) [spring - tx - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Activiti. Spring. SpringTransactionInterceptor. Execute (SpringTransactionInterceptor. Java: 45) [activiti - spring - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Engine. Impl. Interceptor. LogInterceptor. Execute (LogInterceptor. Java: 29) [activiti - engine - 6.0.0. Jar: 6.0.0]
At org.activiti.engine.impl.cfg.Com mandExecutorImpl. Execute (CommandExecutorImpl. Java: 44) [activiti - engine - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Engine. Impl. ProcessEngineImpl. & lt; init> (ProcessEngineImpl. Java: 81) [activiti - engine - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Engine. Impl. CFG. ProcessEngineConfigurationImpl. BuildProcessEngine (ProcessEngineConfigurationImpl. Java: 665) [activiti - engine - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Spring. SpringProcessEngineConfiguration. BuildProcessEngine (SpringProcessEngineConfiguration. Java: 65) [activiti - spring - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Spring. ProcessEngineFactoryBean. GetObject (ProcessEngineFactoryBean. Java: 57) [activiti - spring - 6.0.0. Jar: 6.0.0]
The at org. Activiti. Spring. ProcessEngineFactoryBean. GetObject (ProcessEngineFactoryBean. Java: 32) [activiti - spring - 6.0.0. Jar: 6.0.0]
The at org. Springframework. Beans. Factory. Support. FactoryBeanRegistrySupport. DoGetObjectFromFactoryBean (FactoryBeanRegistrySupport. Java: 171) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. FactoryBeanRegistrySupport. GetObjectFromFactoryBean (FactoryBeanRegistrySupport. Java: 101) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. AbstractBeanFactory. GetObjectForBeanInstance (AbstractBeanFactory. Java: 1818) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. AbstractAutowireCapableBeanFactory. GetObjectForBeanInstance (AbstractAutowireCapableBeanFactory. Java: 1266) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. AbstractBeanFactory. DoGetBean (AbstractBeanFactory. Java: 260) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. AbstractBeanFactory. GetBean (AbstractBeanFactory. Java: 202) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Config. DependencyDescriptor. ResolveCandidate (DependencyDescriptor. Java: 276) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. DefaultListableBeanFactory. AddCandidateEntry (DefaultListableBeanFactory. Java: 1515) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. DefaultListableBeanFactory. FindAutowireCandidates (DefaultListableBeanFactory. Java: 1472) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. DefaultListableBeanFactory. DoResolveDependency (DefaultListableBeanFactory. Java: 1253) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
The at org. Springframework. Beans. Factory. Support. DefaultListableBeanFactory. ResolveDependency (DefaultListableBeanFactory. Java: 1210) [spring - beans - 5.2.5. The jar: 5.2.5. RELEASE]
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