I have the same problem on windows server.
Plesk, after the automatic update to 18.0.60_14244 (previously it was 18.0.59_14022), started showing this error and no longer logs into Plesk:
500 Plesk\Exception\Database - DB query failed: SQLSTATE[HY000] [2002] No connection cloud be made because the target machine actively refused it.
Looking at the log, I found these errors:
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[2024-04-18 23:54:36.489956] MSI (04): Output:
[2024-04-18 23:55:08.894461] MSI (04): Stop service...
[2024-04-18 23:55:08.894461] MSI (04): Start service...
[2024-04-18 23:55:08.894461] MSI (04): Upgrade only the system tables...
[2024-04-18 23:55:08.894461] MSI (04): Restart service...
[2024-04-18 23:55:08.894461] MSI (04): Execute C:\Program Files (x86)\Plesk\MySQL\bin\mysql_upgrade.exe "--defaults-file=\"C:\Program" Files "(x86)\Plesk\MySQL\my.ini --force --upgrade-system-tables --host=. --protocol=pipe --socket=ommited" failed: The --upgrade-system-tables option was used, user tables won't be touched.
...continuing...
[2024-04-18 23:55:08.910084] MSI (04): mysql.transaction_registry OK
[2024-04-18 23:55:08.910084] MSI (04): Phase 2/8: Installing used storage engines... Skipped
[2024-04-18 23:55:08.910084] MSI (04): Phase 3/8: Running 'mysql_fix_privilege_tables'
[2024-04-18 23:55:08.910084] MSI (04): ERROR 2013 (HY000) at line 2581: Lost connection to server during query
[2024-04-18 23:55:08.910084] MSI (04): ERROR 2006 (HY000) at line 2607: Server has gone away
...continuing...
[2024-04-18 23:55:08.988201] MSI (04): ERROR 2006 (HY000) at line 8506: Server has gone away
[2024-04-18 23:55:08.988201] MSI (04): FATAL ERROR: Upgrade failed
[2024-04-18 23:55:08.988201] MSI (04): at (execExtUtilChecked line 160)
[2024-04-18 23:55:08.988201] MSI (04): at Launch mysql_upgrade(mysqlmng_adm::upgradeServerData line 411)
[2024-04-18 23:55:08.988201] MSI (04): Incorrect function. (Error code 1) at Start service PleskSQLServer
[2024-04-18 23:55:08.988201] MSI (04): at (service::startStopService line 997)
[2024-04-18 23:55:08.988201] MSI (04): at Error occurred on starting PleskSQLServer service.
[2024-04-18 23:55:08.988201] MSI (04): Errors in error log file:
[2024-04-18 23:55:08.988201] MSI (04): 2024-04-18 23:55:07 0 Could not open mysql.plugin table: "Can't find file: '.\mysql\plugin.MAI' (errno: 2 "No such file or directory")". Some plugins may be not loaded
[2024-04-18 23:55:08.988201] MSI (04): 2024-04-18 23:55:07 0 Can't open and lock privilege tables: Can't find file: '.\mysql\servers.MAI' (errno: 2 "No such file or directory")
[2024-04-18 23:55:09.003826] MSI (04): 2024-04-18 23:55:07 0 Fatal error: Can't open and lock privilege tables: Can't find file: '.\mysql\db.MAI' (errno: 2 "No such file or directory")
[2024-04-18 23:55:09.003826] MSI (04): 2024-04-18 23:55:07 0 Aborting
[2024-04-18 23:55:09.003826] MSI (04): (mysqlmng_adm::startService line 222)
[2024-04-18 23:55:09.003826] MSI (04): at (mysqlmng_adm::startService line 225)
[2024-04-18 23:55:09.003826] MSI (04): at startService()(mysqlmng_adm::startService line 228)
[2024-04-18 23:55:09.003826] MSI (04): at restartService()(mysqlmng_adm::restartService line 238)
[2024-04-18 23:55:09.003826] MSI (04): at Restart service(mysqlmng_adm::upgradeServerData line 430)
[2024-04-18 23:55:09.003826] MSI (04): at (mysqlmng_adm::upgradeServerData line 436)
[2024-04-18 23:55:09.003826] MSI (04): at Unable to execute console command: '--upgrade-server-data'(vconsoleapp::start line 95)
[2024-04-18 23:55:09.003826] MSI (04): at Unable to execute command: '"C:\Program Files (x86)\Plesk\admin\bin\mysqlmng_adm.exe" --upgrade-server-data'(vconsoleapp::run line 117)
[2024-04-18 23:55:09.003826] MSI (04): Critical action 'Upgrade data of Plesk SQL Server...' failed:
Command "C:\Program Files (x86)\Plesk\admin\bin\mysqlmng_adm.exe" --upgrade-server-data failed with code 1. Output: Stop service...
Start service...
Upgrade only the system tables...
Restart service...
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What is the solution for this case?