i installed xampp version 3.2.1 on my laptop and mysql was working fine on it before but suddenly mysql stopped working while apache and others were working.
when i click on start mysql it displays this error
i use windows 10

我在笔记本电脑上安装了Xampp 3.2.1版，之前MySQL在它上面运行得很好，但突然MySQL停止运行，而阿帕奇和其他公司都在运行。当我点击开始MySQL时，它显示这个错误我使用Windows 10

8:52:32 AM  [mysql]     Status change detected: running
8:52:40 AM  [mysql]     Status change detected: stopped
8:52:40 AM  [mysql]     Error: MySQL shutdown unexpectedly.
8:52:40 AM  [mysql]     This may be due to a blocked port, missing dependencies, 
8:52:40 AM  [mysql]     improper privileges, a crash, or a shutdown by another method.
8:52:40 AM  [mysql]     Press the Logs button to view error logs and check
8:52:40 AM  [mysql]     the Windows Event Viewer for more clues
8:52:40 AM  [mysql]     If you need more help, copy and post this
8:52:40 AM  [mysql]     entire log window on the forums

then i checked the log file and this is what i found there

然后我检查了日志文件，这是我在那里发现的

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2018-06-23 08:52:32 2354 InnoDB: Warning: Using innodb_additional_mem_pool_size is DEPRECATED. This option may be removed in future releases, together with the option innodb_use_sys_malloc and with the InnoDB's internal memory allocator.
180623  8:52:32 [Note] InnoDB: Using mutexes to ref count buffer pool pages
180623  8:52:32 [Note] InnoDB: The InnoDB memory heap is disabled
180623  8:52:32 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions
180623  8:52:32 [Note] InnoDB: Memory barrier is not used
180623  8:52:32 [Note] InnoDB: Compressed tables use zlib 1.2.3
180623  8:52:32 [Note] InnoDB: Not using CPU crc32 instructions
180623  8:52:32 [Note] InnoDB: Initializing buffer pool, size = 16.0M
180623  8:52:32 [Note] InnoDB: Completed initialization of buffer pool
180623  8:52:32 [Note] InnoDB: Highest supported file format is Barracuda.
180623  8:52:32 [Note] InnoDB: 128 rollback segment(s) are active.
180623  8:52:32 [Note] InnoDB: Waiting for purge to start
180623  8:52:33 [Note] InnoDB:  Percona XtraDB (http://www.percona.com) 5.6.22-72.0 started; log sequence number 1600924
180623  8:52:33 [Note] Plugin 'FEEDBACK' is disabled.
180623  8:52:33 [Note] Server socket created on IP: '::'.
180623  8:52:33 [Warning] 'db' entry 'size of datafile is: 1907       should be: 1760

180409 15:17:15 [error] mysql.db: got error: 0 when reading datafile at record: 3

180409 15:17:15 [error] got an error from unknown thread, ha _myisam.cc:952

180409 15:17:15 [Warning] Recove@80409 15:17:15 [Warning] Checking table:   '.\mysql\db'

180409 15:17:15 [ERROR] mysql.db: 1 client is using or hasn't closed the table properly

180409 15:17:15 [ERROR] mysql.db:' had database in mixed case that has been forced to lowercase because lower_case_table_names is set. It will not be possible to remove this privilege using REVOKE.
180623  8:52:33 [ERROR] Missing system table mysql.roles_mapping; please run mysql_upgrade to create it
180623  8:52:33 [ERROR] Incorrect definition of table mysql.event: expected column 'sql_mode' at position 14 to have type set('REAL_AS_FLOAT','PIPES_AS_CONCAT','ANSI_QUOTES','IGNORE_SPACE','IGNORE_BAD_TABLE_OPTIONS','ONLY_FULL_GROUP_BY','NO_UNSIGNED_SUBTRACTION','NO_DIR_IN_CREATE','POSTGRESQL','ORACLE','MSSQL','DB2','MAXDB','NO_KEY_OPTIONS','NO_TABLE_OPTIONS','NO_FIELD_OPTIONS','MYSQL323','MYSQL40','ANSI','NO_AUTO_VALUE_ON_ZERO','NO_BACKSLASH_ESCAPES','STRICT_TRANS_TABLES','STRICT_ALL_TABLES','NO_ZERO_IN_DATE','NO_ZERO_DATE','INVALID_DATES','ERROR_FOR_DIVISION_BY_ZERO','TRADITIONAL','NO_AUTO_CREATE_USER','HIGH_NOT_PRECEDENCE','NO_ENGINE_SUBSTITUTION','PAD_CHAR_TO_FULL_LENGTH'), found type set('REAL_AS_FLOAT','PIPES_AS_CONCAT','ANSI_QUOTES','IGNORE_SPACE','NOT_USED','ONLY_FULL_GROUP_BY','NO_UNSIGNED_SUBTRACTION','NO_DIR_IN_CREATE','POSTGRESQL','ORACLE','MSSQL','DB2','MAXDB','NO_KEY_OPTIONS','NO_TABLE_OPTIONS','NO_FIELD_OPTIONS','MYSQL323','MYSQL40','ANSI','NO_AUTO_VALUE_ON_ZERO','NO_BACKSLASH_ESCAPES','STRICT_TRANS_TABLES','STRICT_A
180623  8:52:33 [ERROR] Event Scheduler: An error occurred when initializing system tables. Disabling the Event Scheduler.
180623  8:52:33 [Warning] Failed to load slave replication state from table mysql.gtid_slave_pos: 1146: Table 'mysql.gtid_slave_pos' doesn't exist
180623  8:52:33 [Warning] Neither --relay-log nor --relay-log-index were used; so replication may break when this MySQL server acts as a slave and has his hostname changed!! Please use '--log-basename=#' or '--relay-log=mysql-relay-bin' to avoid this problem.
180623  8:52:33 [Note] Started replication for '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
'
180623  8:52:33 [ERROR] Master '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
': Slave I/O: Unable to load replication GTID slave state from mysql.gtid_slave_pos: Table 'mysql.gtid_slave_pos' doesn't exist, Internal MariaDB error code: 1146
180623  8:52:33 [Note] Master '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
': Slave SQL thread initialized, starting replication in log 'FIRST' at position 0, relay log '.\mysql-relay-bin-180401@002018@003a51@003a15@0020@005bnote@005d@0020c@003a@005cxampp@005cmysql@005cbin@005cmysqld@002eexe@003a@0020ready@0020for@0020connections@[email protected]' position: 4
180623  8:52:33 [ERROR] Master '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
': Slave I/O: Fatal error: Invalid (empty) username when attempting to connect to the master server. Connection attempt terminated. Internal MariaDB error code: 1593
180623  8:52:33 [ERROR] Failed to open the relay log '.\mysql-relay-bin-version@003a@0020@002710@002e0@002e17@002dmariadb@0027@0020@0020socket@003a@0020@0027@0027@0020@0020port@003a@00203306@0020@0020mariadb@002eorg@0020binary@[email protected]' (relay_log_pos 4)
180623  8:52:33 [ERROR] Master '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
': Slave SQL: Unable to load replication GTID slave state from mysql.gtid_slave_pos: Table 'mysql.gtid_slave_pos' doesn't exist, Internal MariaDB error code: 1146
180623  8:52:33 [Note] Master '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
': Slave I/O thread killed while connecting to master
180623  8:52:33 [ERROR] Could not find target log during relay log initialization
180623  8:52:33 [Note] Master '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
': Slave I/O thread exiting, read up to log 'FIRST', position 4
180623  8:52:33 [ERROR] Initialized Master_info from 'master-version@003a@0020@002710@002e0@002e17@002dmariadb@0027@0020@0020socket@003a@0020@0027@0027@0020@0020port@003a@00203306@0020@0020mariadb@002eorg@0020binary@[email protected]' failed
180623  8:52:33 [Warning] Reading of some Master_info entries failed
180623  8:52:33 [ERROR] Failed to initialize multi master structures
180623  8:52:33 [ERROR] Aborting

180623  8:52:33 [Note] Master '180401 18:51:15 [Note] c:\xampp\mysql\bin\mysqld.exe: ready for connections.
': Error reading relay log event: slave SQL thread was killed
180623  8:52:33 [Note] InnoDB: FTS optimize thread exiting.
180623  8:52:33 [Note] InnoDB: Starting shutdown...
180623  8:52:35 [Note] InnoDB: Shutdown completed; log sequence number 1600934
180623  8:52:35 [Note] C:\xampp\mysql\bin\mysqld.exe: Shutdown complete`

Deleting all files (no folders!) in the /mysql/data folder, except /mysql/data/my.ini and /data/ibdata1 helped in my case.

删除所有文件(无文件夹！)在/mysql/data文件夹中，除了/mysql/data/my.ini和/data/ibdata1对我有帮助之外。

Deleting all master-* files and multi-master.info worked for me.

删除所有master-*文件和多master.info对我起作用了。

Copying files and folders from C:\xampp\mysql\backup to C:\xampp\mysql\data
and removing all my database folders worked for me.
But first try without deleting your database files.

将文件和文件夹从C：\xampp\MySQL\Backup复制到C：\xampp\MySQL\Data，并删除我所有的数据库文件夹。但在不删除数据库文件的情况下先尝试。

Delete mysql.pid file.
you can delete also other master-* files

删除mysql.pid文件。您还可以删除其他master-*文件

Go to C:\xampp\mysql\data and delete all master files.
multi-master
master-version

转到C：\xampp\MySQL\Data并删除所有主文件。多母版母版