Using previous MySQL data folder on new MySQL installation

Question

If I could have made a proper SQL dump/backup I would have, but OS gave out and could only log into SafeMode, where I couldn't start the MySQL server. Therefore, I could only manually backup the file directories.

• I have a saved file copy of C:\ProgramData\MySQL\MySQL Server 8.0
• I have a saved file copy of C:\Program Files\MySQL\MySQL Server 8.0

I'm now running on a new installation of Windows and trying to start this old server up for a few minutes so I can log on from Workbench and make a proper SQL database dump which will I import on a new MySQL installation later.

Consequently, moving the mentioned files in their respective locations - Program Files and ProgramData.

Opening up PowerShell (with Admin rights) and doing:

mysqld --defaults-file="C:\ProgramData\MySQL\MySQL Server 8.0" --console

and I get a few hundred lines on the screen that contain the following:

2020-04-10T05:28:56.725818Z 0 [ERROR] [MY-011972] [InnoDB] Your database may be corrupt or you may have copied the InnoDB tablespace but not the InnoDB log files. Please refer to http://dev.mysql.com/doc/refman/8.0/en/forcing-innodb-recovery.html for information about forcing recovery.
2020-04-10T05:28:56.734460Z 0 [ERROR] [MY-011971] [InnoDB] Tablespace 'innodb_undo_001' Page [page id: space=4294967279, page number=5] log sequence number 1339677380 is in the future! Current system log sequence number 19081380.

Followed by:

2020-04-10T05:28:56.740834Z 0 [ERROR] [MY-011972] [InnoDB] Your database may be corrupt or you may have copied the InnoDB tablespace but not the InnoDB log files. Please refer to http://dev.mysql.com/doc/refman/8.0/en/forcing-innodb-recovery.html for information about forcing recovery.
2020-04-10T05:28:56.757259Z 0 [System] [MY-010229] [Server] Starting crash recovery...
2020-04-10T05:28:56.769215Z 0 [System] [MY-010232] [Server] Crash recovery finished.
2020-04-10T05:28:57.695386Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2020-04-10T05:28:57.765911Z 0 [System] [MY-010931] [Server] C:\Program Files\MySQL\MySQL Server 8.0\bin\mysqld.exe: ready for connections. Version: '8.0.13'  socket: ''  port: 3306  MySQL Community Server - GPL.
2020-04-10T05:28:57.926850Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060

Great, at least its running.

I can now connect but no databases.

• What can I do / how should I proceed to successfully get those databases back temporarily?

UPDATE:

Removed the innodb_undo_001 and innodb_undo_002 files from the Data directory and relaunched.

Getting this:

PS C:\Program Files\MySQL\MySQL Server 8.0\bin> .\mysqld --defaults-file="C:\ProgramData\MySQL\MySQL Server 8.0\my.ini" --console                                                               2020-04-10T05:55:29.555478Z 0 [Warning] [MY-010915] [Server] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release.
2020-04-10T05:55:29.558313Z 0 [System] [MY-010116] [Server] C:\Program Files\MySQL\MySQL Server 8.0\bin\mysqld.exe (mysqld 8.0.13) starting as process 3028
2020-04-10T05:55:31.394427Z 1 [Warning] [MY-012351] [InnoDB] Tablespace 1, name 'sys/sys_config', file '.\sys\sys_config.ibd' is missing!
2020-04-10T05:55:32.808645Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2020-04-10T05:55:32.856154Z 0 [System] [MY-010931] [Server] C:\Program Files\MySQL\MySQL Server 8.0\bin\mysqld.exe: ready for connections. Version: '8.0.13'  socket: ''  port: 3306  MySQL Community Server - GPL.
2020-04-10T05:55:32.898055Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060

Running but no databases present.

Tried the Innodb-force-recovery approach - nothing happens. Same as before.

Answer 1

Ok, assuming that all the files are not corrupted, you can try the following:

1. Create a new folder (in a different drive if possible). Name it as test or something. Then copy all files from the C:\Program Files\MySQL\MySQL Server 8.0 directory into the new folder.

*note: if you don't have my.ini file in the folder, copy it from the C:\ProgramData\MySQL\MySQL Server 8.0 directory into the folder.

2. Open my.ini file and change the following:

3. Go back to the top of my.ini file and change: after changing above, copy the whole line from mysqld --install MySQLXY .. to the end. Don't copy the first # at the beginning. Then save the my.ini file.

4. Open command prompt (cmd) as administrator then do this:

*installing the service manually using cmd.

5. Go to services (keyboard shortcut windows button+R then type services.msc then press ENTER or OK), find the newly installed MySQL service and click start.

6. Try connecting to db.