I have also dealt with this exception after a fully working context.xml setup was adjusted. I didn't want environment details in the context.xml, so I took them out and saw this error. I realized I must fully create this datasource resource in code based on System Property JVM -D args.
Original error with just user/pwd/host removed:
org.apache.tomcat.jdbc.pool.ConnectionPool init
SEVERE: Unable to create initial connections of pool.
Removed entire contents of context.xml and try this:
Initialize on startup of app server the datasource object sometime before using first connection. If using Spring this is good to do in an @Configuration bean in @Bean Datasource constructor.
package to use: org.apache.tomcat.jdbc.pool.*
PoolProperties p = new PoolProperties();
p.setUrl(jdbcUrl);
p.setDriverClassName(driverClass);
p.setUsername(user);
p.setPassword(pwd);
p.setJmxEnabled(true);
p.setTestWhileIdle(false);
p.setTestOnBorrow(true);
p.setValidationQuery("SELECT 1");
p.setTestOnReturn(false);
p.setValidationInterval(30000);
p.setValidationQueryTimeout(100);
p.setTimeBetweenEvictionRunsMillis(30000);
p.setMaxActive(100);
p.setInitialSize(5);
p.setMaxWait(10000);
p.setRemoveAbandonedTimeout(60);
p.setMinEvictableIdleTimeMillis(30000);
p.setMinIdle(5);
p.setLogAbandoned(true);
p.setRemoveAbandoned(true);
p.setJdbcInterceptors(
"org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;"+
"org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer");
org.apache.tomcat.jdbc.pool.DataSource ds = new org.apache.tomcat.jdbc.pool.DataSource();
ds.setPoolProperties(p);
return ds;