Confluence server does not start after upgrade

[Seven Network]

When trying to upgrade from 7.11.1 to a higher version, Confluence doesn't start.

No apparent critical errors in the startup log.

Database log reads as follows:

```

2021-08-26 3:29:42 52 [Warning] Aborted connection 52 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 38 [Warning] Aborted connection 38 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 37 [Warning] Aborted connection 37 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 54 [Warning] Aborted connection 54 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 35 [Warning] Aborted connection 35 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 49 [Warning] Aborted connection 49 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 36 [Warning] Aborted connection 36 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 48 [Warning] Aborted connection 48 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 47 [Warning] Aborted connection 47 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 46 [Warning] Aborted connection 46 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 45 [Warning] Aborted connection 45 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 44 [Warning] Aborted connection 44 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 51 [Warning] Aborted connection 51 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 50 [Warning] Aborted connection 50 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 39 [Warning] Aborted connection 39 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 34 [Warning] Aborted connection 34 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 40 [Warning] Aborted connection 40 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 41 [Warning] Aborted connection 41 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 42 [Warning] Aborted connection 42 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets) 2021-08-26 3:29:42 43 [Warning] Aborted connection 43 to db: 'confluence' user: 'confluence' host: 'localhost' (Got an error reading communication packets)

```

[Nic Brough -Adaptavist-]

"Aborted connection" suggests a networking error, your database and local network are not configured correctly.  This isn't something we can help you with really, it's not a problem with Confluence, all we can do is tell you that you need to fix the connection to the database.