Cannot start MySQL - server quit "w/o updating PID file" (PID file missing) I have been researching this problem for two days, and I know there are many other posts about it. But the solutions are always "fix the permissions". That does not solve it for me. I have recursively changed the permissions on the symbolic and original directory trees to 777 and I still get the error. Not only is the PID file not being updated, but the error file is not being written either, though the error message in Terminal when I try to start MySQL says that it is. That does suggest something is preventing processes from writing to the directory, but it's not file permissions.

Here's the full error message:

Starting MySQL
.Logging to '/usr/local/mysql/data/Sheryls-MacBook-Pro.local.err'.
/usr/local/mysql/bin/mysqld_safe: line 198: 11197 Trace/BPT trap: 5       nohup /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/usr/local/mysql/data --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=Sheryls-MacBook-Pro.local.err --pid-file=/usr/local/mysql/data/Sheryls-MacBook-Pro.local.pid &lt; /dev/null > /dev/null 2>&amp;1
 ERROR! The server quit without updating PID file (/usr/local/mysql/data/Sheryls-MacBook-Pro.local.pid).

Also, here are my permissions, so you can see this is not the problem:

Sheryls-MacBook-Pro:mysql Sheryl$ ls -laF
total 48
drwxrwxrwx  13 root    wheel     442 Apr 13 14:48 ./
drwxr-xr-x   9 root    wheel     306 Apr 13 14:48 ../
-rwxrwxrwx   1 root    wheel   17987 Dec 27 22:46 COPYING*
-rwxrwxrwx   1 root    wheel    2478 Dec 27 22:46 README*
drwxrwxrwx  40 root    wheel    1360 Jan 24 08:41 bin/
drwxrwxrwx   6 _mysql  _mysql    204 Apr 13 14:48 data/
drwxrwxrwx   5 root    wheel     170 Jan 24 08:41 docs/
drwxrwxrwx  50 root    wheel    1700 Jan 24 08:41 include/
drwxrwxrwx   2 _mysql  _mysql     68 Apr 13 14:48 keyring/
drwxrwxrwx  11 root    wheel     374 Apr 13 14:48 lib/
drwxrwxrwx   4 root    wheel     136 Jan 24 08:41 man/
drwxrwxrwx  39 root    wheel    1326 Jan 24 08:41 share/
drwxrwxrwx   6 root    wheel     204 Jan 24 08:41 support-files/


I'm running MacOS 10.11.6 (El Capitan). Apache is enabled and working, and PHP is enabled and working. Both are the versions that came pre-installed. MySQL is v5.7.21. I've removed and reinstalled it 3 times now. This version does not come with a configuration file.

Should I try an older version of MySQL?? 

Does anyone have an answer to this problem?
I solved it! When I finally got it to write an error log (needed to fix the permissions for that) and looked inside the error log, I saw it was missing the symbol _clock_gettime(). When I googled that, I discovered MacOS didn't add that symbol until OSX 10.12, and I'm running 10.11 (so as not to break Dreamweaver CS6).

I uninstalled MySQL 5.7.21 and looked for the latest version of MySQL that supported El Capitan (10.11), which turned out to be 5.7.16. I installed that, and now it's running fine.