Can't start mysql after downgrade, can't run mysql_upgrade, can't change root password
<p>I downgraded a mysql server from 5.7.14 to 5.6.32.</p>
<p>After doing so, I presumed I was supposed to run mysql_upgrade, according to the instructions I came across.</p>
<p>However, to do so, I need to supply the root user/p, which I have. However, it doesn't appear to be accepting those when I attempt to do so:</p>
<blockquote>
<p>mysql_upgrade -u root -p</p>
<p>Enter password:</p>
<p>Looking for 'mysql' as: mysql</p>
<p>Looking for 'mysqlcheck' as: mysqlcheck</p>
<p>Error: Failed while fetching Server version! Could be due to unauthorized access.</p>
<p>FATAL ERROR: Upgrade failed</p>
</blockquote>
<p>So I attempted to reset the password, by creating an init file with something like:
SET PASSWORD FOR 'root'@'localhost' = PASSWORD('abcd1234');
and then calling it with mysqld_safe --init-file=/home/root/mysql-init &amp;</p>
<p>But this doesn't seem to work, presumably because mysql can't startup correctly and throws an error.</p>
<pre><code>0802 12:50:45 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

2016-08-02 12:50:46 0 [Warning] TIMESTAMP with implicit DEFAULT value is 

2016-08-02 12:50:46 0 [Note] /usr/sbin/mysqld (mysqld 5.6.32) starting as process 2635 ...

2016-08-02 12:50:46 2635 [Note] Plugin 'FEDERATED' is disabled.

/usr/sbin/mysqld: Unknown storage engine 'InnoDB'

2016-08-02 12:50:46 2635 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.

2016-08-02 12:50:46 2635 [Note] InnoDB: Using atomics to ref count buffer pool pages

2016-08-02 12:50:46 2635 [Note] InnoDB: The InnoDB memory heap is disabled

2016-08-02 12:50:46 2635 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins

2016-08-02 12:50:46 2635 [Note] InnoDB: Memory barrier is not used

2016-08-02 12:50:46 2635 [Note] InnoDB: Compressed tables use zlib 1.2.3

2016-08-02 12:50:46 2635 [Note] InnoDB: Using Linux native AIO

2016-08-02 12:50:46 2635 [Note] InnoDB: Using CPU crc32 instructions

2016-08-02 12:50:46 2635 [Note] InnoDB: Initializing buffer pool, size = 128.0M

2016-08-02 12:50:46 2635 [Note] InnoDB: Completed initialization of buffer pool

2016-08-02 12:50:46 2635 [Note] InnoDB: Highest supported file format is Barracuda.

2016-08-02 12:50:46 2635 [Note] InnoDB: The log sequence numbers 2512357 and 

2512357 in ibdata files do not match the log sequence number 2512396 in $

2016-08-02 12:50:46 2635 [Note] InnoDB: Database was not shutdown normally!

2016-08-02 12:50:46 2635 [Note] InnoDB: Starting crash recovery.

2016-08-02 12:50:46 2635 [Note] InnoDB: Reading tablespace information from the .ibd files...

2016-08-02 12:50:46 2635 [Note] InnoDB: Restoring possible half-written data pages

2016-08-02 12:50:46 2635 [Note] InnoDB: from the doublewrite buffer...

InnoDB: wrong number of columns in SYS_INDEXES record

InnoDB: wrong number of columns in SYS_INDEXES record

InnoDB: wrong number of columns in SYS_INDEXES record

InnoDB: wrong number of columns in SYS_INDEXES record

InnoDB: wrong number of columns in SYS_INDEXES record
17:50:46 UTC - mysqld got signal 11 ;
</code></pre>
<p>This would seem to leave me in a loop where I can't run mysql_upgrade to upgrade the db, and yet I can't successfully reset the root password (Although I'm 99.9% sure I've got the correct root password, it just doesn't appear to be accepting it.)</p>
<p>Stack trace..</p>
<pre><code>Thread pointer: 0x0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...

stack_bottom = 0 thread_stack 0x40000

/usr/sbin/mysqld(my_print_stacktrace+0x35)[0x8e2375]

/usr/sbin/mysqld(handle_fatal_signal+0x494)[0x666da4]

/lib64/libpthread.so.0[0x398620f790]

/usr/sbin/mysqld[0xac1017]

/usr/sbin/mysqld[0xac25fd]

/usr/sbin/mysqld[0xa3de77]

/usr/sbin/mysqld[0x9822dd]

/usr/sbin/mysqld(_Z24ha_initialize_handlertonP13st_plugin_int+0x48)[0x5aa958]

/usr/sbin/mysqld[0x6f01e1]

/usr/sbin/mysqld(_Z11plugin_initPiPPci+0xbb6)[0x6f4046]

/usr/sbin/mysqld[0x59ce38]

/usr/sbin/mysqld(_Z11mysqld_mainiPPc+0x425)[0x5a2055]

/lib64/libc.so.6(__libc_start_main+0xfd)[0x3985e1ed5d]

/usr/sbin/mysqld[0x593ba5]
</code></pre>
<p>Any suggestions? Thanks</p>