[FIXED] MAMP: Unable to start MySQL after upgrade from 5.5 to 5.7

Issue

I upgraded mySQL from 5.5. to 5.7. I am not being able to make MAMP running MYSQL. Error log gives that:

160617 14:45:13 mysqld_safe Starting mysqld daemon with databases from /Applications/MAMP/db/mysql
2016-06-17T09:45:13.908521Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2016-06-17T09:45:13.976451Z 0 [Warning] Insecure configuration for --secure-file-priv: Current value does not restrict location of generated files. Consider setting it to a valid, non-empty path.
2016-06-17T09:45:13.976701Z 0 [Note] /Applications/MAMP/Library/bin/mysqld (mysqld 5.7.9) starting as process 28255 ...
2016-06-17T09:45:14.111330Z 0 [Warning] Setting lower_case_table_names=2 because file system for /Applications/MAMP/db/mysql/ is case insensitive
2016-06-17T09:45:14.136797Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2016-06-17T09:45:14.136828Z 0 [Note] InnoDB: Uses event mutexes
2016-06-17T09:45:14.136838Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2016-06-17T09:45:14.136849Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.3
2016-06-17T09:45:14.137452Z 0 [Note] InnoDB: Number of pools: 1
2016-06-17T09:45:14.145153Z 0 [Note] InnoDB: Not using CPU crc32 instructions
2016-06-17T09:45:14.230174Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
2016-06-17T09:45:14.299060Z 0 [Note] InnoDB: Completed initialization of buffer pool
2016-06-17T09:45:14.395299Z 0 [ERROR] InnoDB: ./ib_logfile0 can't be opened in read-write mode.
2016-06-17T09:45:14.395336Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Generic error
2016-06-17T09:45:14.707209Z 0 [ERROR] Plugin 'InnoDB' init function returned error.
2016-06-17T09:45:14.707274Z 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2016-06-17T09:45:14.707335Z 0 [ERROR] Failed to initialize plugins.
2016-06-17T09:45:14.707361Z 0 [ERROR] Aborting

2016-06-17T09:45:14.707400Z 0 [Note] Binlog end
2016-06-17T09:45:14.707585Z 0 [Note] Shutting down plugin 'CSV'
2016-06-17T09:45:14.719175Z 0 [Note] /Applications/MAMP/Library/bin/mysqld: Shutdown complete

160617 14:45:14 mysqld_safe mysqld from pid file /Applications/MAMP/tmp/mysql/mysql.pid ended

Solution

Fix

Open up a terminal and chown MAMP's mysql database folder :

sudo chown -R `whoami`:admin /Applications/MAMP/db/mysql

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Explanation

I just ran into the same error, the hint is here :

[ERROR] InnoDB: ./ib_logfile0 can't be opened in read-write mode.

It means that the user running mysqld isn't allowed to read-write. But _mysql is the owner of this file :

-rw-r----- 1 _mysql admin 50331648 10 avr 22:35 ib_logfile0

I ran ps -axj | grep mysql right after launching the server, and saw I was the owner of mysqld, instead of being owned by _mysql.

It's a breaking change, I think we should have been warned in the release note.

Answered By - Bigood