I updated confluence on my machine and now it won't start with the Database connection failed error. The contents of the atlassian-confluence.log is full of the following:
2018-08-15 21:25:06,854 WARN [C3P0PooledConnectionPoolManager[identityToken->1hge13x9xgr65m2f68yko|ec82954]-HelperThread-#1] [mchange.v2.resourcepool.BasicResourcePool] log com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@15495128 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception:
org.h2.jdbc.JdbcSQLException: General error: "java.lang.RuntimeException: rowCount expected 139699 got 135939 T187.I847" [50000-176]