[FIXED] How to solve "Error: MySQL shutdown unexpectedly"?

Issue

When I open XAMPP and click start MySQL button and it gives me an error. I had started it just before, but now it isn't working.

12:19:12 PM [mysql] Attempting to start MySQL app...
12:19:12 PM [mysql] Status change detected: running
12:19:13 PM [mysql] Status change detected: stopped
12:19:13 PM [mysql] Error: MySQL shutdown unexpectedly.
12:19:13 PM [mysql] This may be due to a blocked port, missing dependencies,
12:19:13 PM [mysql] improper privileges, a crash, or a shutdown by another method
12:19:13 PM [mysql] Press the Logs button to view error logs and check
12:19:13 PM [mysql] the Windows Event Viewer for more clues
12:19:13 PM [mysql] If you need more help, copy and post this
12:19:13 PM [mysql] entire log window on the forums

Here is the contents of the error log:

2013-08-02 12:19:12 4536 [Note] Plugin 'FEDERATED' is disabled.
2013-08-02 12:19:12 f64 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.
2013-08-02 12:19:12 4536 [Note] InnoDB: The InnoDB memory heap is disabled
2013-08-02 12:19:12 4536 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions
2013-08-02 12:19:12 4536 [Note] InnoDB: Compressed tables use zlib 1.2.3
2013-08-02 12:19:12 4536 [Note] InnoDB: Not using CPU crc32 instructions
2013-08-02 12:19:12 4536 [Note] InnoDB: Initializing buffer pool, size = 16.0M
2013-08-02 12:19:12 4536 [Note] InnoDB: Completed initialization of buffer pool
2013-08-02 12:19:12 4536 [Note] InnoDB: Highest supported file format is Barracuda.
2013-08-02 12:19:12 4536 [Note] InnoDB: The log sequence numbers 0 and 0 in ibdata files do not match the log sequence number 1616798 in the ib_logfiles!
2013-08-02 12:19:12 4536 [Note] InnoDB: Database was not shutdown normally!
2013-08-02 12:19:12 4536 [Note] InnoDB: Starting crash recovery.
2013-08-02 12:19:12 4536 [Note] InnoDB: Reading tablespace information from the .ibd files...

The most important error message is here:

2013-08-02 12:19:12 4536 [ERROR] InnoDB:
Attempted to open a previously opened tablespace.
Previous tablespace mysql/innodb_table_stats uses space ID: 1 at filepath: .\mysql\innodb_table_stats.ibd.
Cannot open tablespace xat/payments which uses space ID: 1 at filepath: .\xat\payments.ibd

The rest of the log:

InnoDB: Error: could not open single-table tablespace file .\xat\payments.ibd
InnoDB: We do not continue the crash recovery, because the table may become
InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.
InnoDB: To fix the problem and start mysqld:
InnoDB: 1) If there is a permission problem in the file and mysqld cannot
InnoDB: open the file, you should modify the permissions.
InnoDB: 2) If the table is not needed, or you can restore it from a backup,
InnoDB: then you can remove the .ibd file, and InnoDB will do a normal
InnoDB: crash recovery and ignore that table.
InnoDB: 3) If the file system or the disk is broken, and you cannot remove
InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf
InnoDB: and force InnoDB to continue crash recovery here.

What is the cause of these errors and how can I rectify them?

Solution

IMPORTANT: do NOT delete ibdata1 file. You could destroy all your databases.

Instead, first try using the MySQL backup folder which is included with XAMPP. So do next steps:

1. Rename folder mysql/data to mysql/data_old
2. Make a copy of mysql/backup folder and name it as mysql/data
3. Copy all your database folders from mysql/data_old into mysql/data (except mysql, performance_schema, and phpmyadmin folders)
4. Copy mysql/data_old/ibdata1 file into mysql/data folder
5. Start MySQL from XAMPP control panel

And, voilà!

Answered By - Fabrizio Valencia

Answer Checked By - Dawn Plyler (PHPFixing Volunteer)