Error: Table '.\mysql\db' is marked as crashed and last (automatic?) repair failed

1. Introduction

One of the most frustrating issues developers face while working with XAMPP on Windows is when MySQL/MariaDB refuses to start, even though the logs initially look normal.

In this case, MariaDB:

• Appears to start
• Initializes InnoDB correctly
• Then silently exits
• Does not listen on port 3306
• Shows no running mysqld process

Eventually, when started in console mode, it fails with a fatal privilege table error.

This tutorial explains:

• How to diagnose the issue correctly
• Why the problem happens
• How to safely repair the MySQL system tables
• How to verify the fix
• What to do if repair fails

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2. Initial Symptoms Observed

You experienced the following symptoms:

• XAMPP MySQL shows “Starting” and then stops
• netstat -ano | findstr :3306 shows no output
• tasklist | findstr mysqld shows no running process
• mysql_error.log shows only startup messages, no shutdown reason
• MySQL is not accessible from phpMyAdmin or applications

These symptoms usually indicate MySQL is crashing after startup, not failing to start.

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3. First Diagnostic Checks

3.1 Check if MySQL is listening on port 3306

Command:

netstat -ano | findstr :3306

Result:

• No output → MySQL is not running or not bound to the port

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3.2 Check if mysqld process exists

Command:

tasklist | findstr /I mysqld

Result:

• No output → mysqld.exe is not running

This confirms MySQL is crashing or exiting.

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4. Checking the MySQL Error Log

File location:

C:\xampp\mysql\data\mysql_error.log

Command used:

powershell -Command "Get-Content 'C:\xampp\mysql\data\mysql_error.log' -Tail 120"

Observation:

• Only startup logs
• No explicit crash reason
• Indicates the real error is occurring before logging fully initializes

At this stage, the correct next step is to run MySQL manually in console mode.

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5. Running MySQL in Console Mode (Critical Step)

This step reveals the actual root cause.

Command:

cd C:\xampp\mysql\bin
mysqld --console

Actual Error Found:

[ERROR] mysqld: Table '.\mysql\db' is marked as crashed and last (automatic?) repair failed
[ERROR] Fatal error: Can't open and lock privilege tables
[ERROR] Aborting

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6. Understanding the Root Cause

What is mysql\db?

• It is a system privilege table
• Stored inside:C:\xampp\mysql\data\mysql\
• Controls:
  • Database access
  • User permissions
  • Host-level grants

Why this causes MySQL to stop

MariaDB cannot start without valid privilege tables.
If mysql\db is corrupted:

• Authentication cannot initialize
• Server aborts immediately
• Port is never opened
• MySQL exits silently

This is not a user database issue — it is a system table corruption.

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7. Recommended Fix (Safe and Correct)

Method 1: Repair System Tables Using mysqlcheck

This method is safe, non-destructive, and should always be tried first.

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Step 1: Stop MySQL Completely

From XAMPP Control Panel:

• Click Stop on MySQL

Verify:

tasklist | findstr /I mysqld

No output means it is fully stopped.

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Step 2: Start MySQL Without Privilege Checks

This allows MySQL to start even if system tables are broken.

Run Command Prompt as Administrator:

cd C:\xampp\mysql\bin
mysqld --skip-grant-tables --skip-networking --console

Important notes:

• Keep this window open
• MySQL will appear to “hang” — this is normal
• Networking is disabled for safety

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Step 3: Repair the MySQL System Tables

Open another Command Prompt as Administrator.

Run:

cd C:\xampp\mysql\bin
mysqlcheck -u root --repair mysql

Then optimize (recommended):

mysqlcheck -u root --optimize mysql

This repairs:

• mysql.db
• Other privilege-related system tables
• Internal metadata

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Step 4: Stop the Temporary Server

Go back to the first console window and press:

Ctrl + C

This safely shuts down the skip-grant MySQL instance.

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Step 5: Start MySQL Normally

From XAMPP Control Panel:

• Click Start on MySQL

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Step 6: Verify MySQL Is Running

Check port:

netstat -ano | findstr :3306

Check process:

tasklist | findstr /I mysqld

If both show output, MySQL is running successfully.

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8. Alternative Repair Method (Manual SQL Repair)

Use this only if mysqlcheck fails.

Step 1: Start MySQL in skip-grant mode

mysqld --skip-grant-tables --skip-networking --console

Step 2: Connect to MySQL

mysql -u root

Step 3: Run manual repairs

USE mysql;
REPAIR TABLE db;
REPAIR TABLE user;
REPAIR TABLE tables_priv;
REPAIR TABLE columns_priv;
REPAIR TABLE procs_priv;
FLUSH PRIVILEGES;
EXIT;

Stop the server (Ctrl+C) and start MySQL normally.

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9. Last-Resort Recovery (Only If Repair Fails)

If tables are beyond repair:

Step 1: Backup existing system tables

C:\xampp\mysql\data\mysql  →  mysql_backup

Step 2: Restore fresh system tables

• Check if this folder exists:C:\xampp\mysql\backup\mysql
• Copy it to:C:\xampp\mysql\data\

Step 3: Start MySQL

• Reset users/passwords if required

This recreates a clean MySQL system schema.

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10. Why This Problem Happens

Common reasons include:

• Improper shutdown or power loss
• Windows force restart
• Antivirus locking .frm or .MYI files
• Disk write interruption
• Manual file copy inside mysql system folder

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11. Prevention Tips

• Always stop MySQL before shutting down Windows
• Exclude C:\xampp\mysql\data from antivirus scanning
• Avoid copying system tables between machines
• Keep regular database backups
• Do not manually edit files inside mysql system database

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12. Final Summary

• MySQL was not failing to start, it was crashing
• The root cause was a corrupted privilege table
• Running mysqld --console revealed the real error
• Repairing system tables resolved the issue
• No user database data needed to be deleted