title: How to solve "Error: MySQL shutdown unexpectedly"?
body: <p>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.</p>
  
  <blockquote>
    <p>12:19:12 PM [mysql] Attempting to start MySQL app...<br>
    12:19:12 PM [mysql] Status change detected: running<br>
    12:19:13 PM [mysql] Status change detected: stopped<br>
    12:19:13 PM [mysql] Error: MySQL shutdown unexpectedly.<br>
    12:19:13 PM [mysql] This may be due to a blocked port, missing dependencies,<br>
    12:19:13 PM [mysql] improper privileges, a crash, or a shutdown by another method<br>
    12:19:13 PM [mysql] Press the Logs button to view error logs and check<br>
    12:19:13 PM [mysql] the Windows Event Viewer for more clues<br>
    12:19:13 PM [mysql] If you need more help, copy and post this<br>
    12:19:13 PM [mysql] entire log window on the forums  </p>
  </blockquote>
  
  <p>Here is the contents of the error log:</p>
  
  <blockquote>
    <p>2013-08-02 12:19:12 4536 [Note] Plugin 'FEDERATED' is disabled.<br>
    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.<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: The InnoDB memory heap is disabled<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Compressed tables use zlib 1.2.3<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Not using CPU crc32 instructions<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Initializing buffer pool, size = 16.0M<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Completed initialization of buffer pool<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Highest supported file format is Barracuda.<br>
    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!<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Database was not shutdown normally!<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Starting crash recovery.<br>
    2013-08-02 12:19:12 4536 [Note] InnoDB: Reading tablespace information from the .ibd files...  </p>
  </blockquote>
  
  <p>The most important error message is here:</p>
  
  <blockquote>
    <p><strong>2013-08-02 12:19:12 4536 [ERROR] InnoDB:</strong><br>
    Attempted to open a previously opened tablespace.<br>
    Previous tablespace <em>mysql/innodb_table_stats</em> uses space ID: 1 at filepath: <em>.\mysql\innodb_table_stats.ibd</em>.<br>
    Cannot open tablespace <em>xat/payments</em> which uses space ID: 1 at filepath: <em>.\xat\payments.ibd</em></p>
  </blockquote>
  
  <p>The rest of the log:</p>
  
  <blockquote>
    <p>InnoDB: Error: could not open single-table tablespace file .\xat\payments.ibd<br>
    InnoDB: We do not continue the crash recovery, because the table may become<br>
    InnoDB: corrupt if we cannot apply the log records in the InnoDB log to it.<br>
    InnoDB: To fix the problem and start mysqld:<br>
    InnoDB: 1) If there is a permission problem in the file and mysqld cannot<br>
    InnoDB: open the file, you should modify the permissions.<br>
    InnoDB: 2) If the table is not needed, or you can restore it from a backup,<br>
    InnoDB: then you can remove the .ibd file, and InnoDB will do a normal<br>
    InnoDB: crash recovery and ignore that table.<br>
    InnoDB: 3) If the file system or the disk is broken, and you cannot remove<br>
    InnoDB: the .ibd file, you can set innodb_force_recovery > 0 in my.cnf<br>
    InnoDB: and force InnoDB to continue crash recovery here.</p>
  </blockquote>
  
  <p>What is the cause of these errors and how can I rectify them?</p>