Top 11 Common Errors in MySQL

MySQL is the most common database that programmers utilize for various purposes. It is used for various tasks like e-commerce, logging applications, data warehousing, etc. However, most people use it for the sole purpose of a web database. However, everyday users get easily acquainted with it. But, they also face some common errors in MySQL that can be easily managed and resolved. 

In this blog, we will talk about the errors of MySQL. As to fix any error, you should be fully aware of its source and cause. We will give you the top 11 MySQL errors that users face while operating the database. It will also make you understand the user’s query, How do I fix MySQL errors?.

But before that, let us go through the reasons that show why we should be aware of the errors of MySQL in detail.

Reasons to Get Familiar with MySQL Errors

The following points give us the reasons that emphasize the need to know about the common errors in MySQL.

  • Knowing about the errors in detail can help us know more about the problem that is creating the error, which can eventually help in solving it.
  • Some errors do not need manual solutions but are occurring due to some missing prerequisites that need to be done. Proper knowledge of the MySQL error helps in identifying those issues.
  • It helps in the development aspect of the user as knowing about the errors in depth increases the chances to avoid them during the ongoing work.

All the above reasons show the necessity for knowing about the common errors in MySQL. Now, let us not waste time and move forward towards the top 11 MySQL problems and solutions.

MySQL Errors List

1. Access Denied Error

It is the most common error of MySQL that is encountered at least once by every MySQL user. It mainly occurs because of the connectivity issues with the  MySQL Server. 

If you face this error, the first things that you should check are that the appropriate permissions are granted to the database. Moreover, the incorrect username and passwords can also pop up this error. 

2. MySQL Server Lost Connection

How do I know if MySQL server is connected, Why I Cannot connect to MySQL server?. These are the most asked questions when you face the lost connections error. It is also considered one of the common errors in MySQL databases. It has not one but multiple causes that can create it. However, the most frequent reason that this error occurs is due to the fact the server gets timed out and closes the connection.

As per the default settings, the connection is set to be closed at 8 hours if there is no change in the database. This time limit can also be changed by using a variable like wait timeout after starting the mysqld.

Another reason to get the server lost error is that you have served a “close” on your MySQL connection and then tried to execute a query on the closed connection. This error is shown in the database in the below-mentioned ways.

CR_SERVER_GONE_ERROR – In this, you cannot send a query to the server.

CR_SERVER_LOST – You would not get a solution to your question even if you can ask the query.

One more probable reason for these common errors in MySQL is that the user may have killed the running thread through kill #threadid#. For this, you can also verify the thread by running the mysqladmin version and viewing the uptime.

Apart from these, there are other reasons for this error, like sending a query to the server that is not correct or too big, etc. 

3. Blocked Host Name

When this error shows up, it is displayed to the user as below.

Host ‘host_name’ is blocked because of many connection errors.

Unblock with ‘mysqladmin flush-hosts’

You get this error when the MySQL server gets the maximum number of requests from the host shown as ‘hostname’ in the error, and they have been interrupted in the middle. Once this happens, the mysqld interprets that something is wrong and blocks all the further connections from the site.

Users always ask questions regarding this error, like When connecting to MySQL what will happen if no hostname is provided?. It can be resolved by running the command mysqladmin flush-hosts. The connection error value is also set to 10 by default in the MySQL server. It means that the database will block the host automatically after 10 errors.

4. Too Many connections Error

As the name suggests, the error occurs when there are already maximum connections done to some other client connections. The default value for maximum connections in the MySQL database is 100. However, you can change this value by restarting mysqld with the value that you want for maximum connections using the max_connections variable.

Also, there are different conditions for different users in terms of maximum connection. Users on Linux and Solaris are permitted to support around 500 to 2000 connections simultaneously. Although, it depends on the RAM they are using and their clients. 

Now, moving further to see more common errors in MySQL.

5. Packet Too Large Error

If the MySQL database gets a packet that is bigger than the allowed (max_allowed_packet) default value, then this error shows up. 

The default values of packets are different according to the different versions of MySQL. For MySQL 3.23, the default biggest value is 16M whereas, for MySQL 4.0.1, there is no upper limit but is dependent on the memory you have left on your server.

6. Table is Full Error

In this error, the error occurs due to the table in MySQL. It has mainly two reasons, namely, when the table has reached its limit size and when the disk has become full.

This error can be easily avoided by using the  -O tmp_table_size=# option in the MySQL database to increase the temporary table size. Furthermore, you also have an option to initiate the MySQL database with the –big-table command to avoid this error afterward. Similarly, all the common errors in MySQL can be resolved using a command after knowing about the error.

7. Cannot Create/Write to File Error

When the MySQL database fails to create a temporary file, it generates this error in the below form.

Can’t create/write to file ‘\\sqla3fe_0.ism’

You can fix this error by using the –tmpdir=path command in MySQL. In addition to that, you can also attach the below command to your database to avoid this error.

[mysqld]

tmpdir=C:/temp

8. Command Out of Sync Error

There is a proper order of calling the commands in the MySQL database. However, if you call the client commands in the wrong order, you are left with this Out of Sync error.

Any command that needs a command before it for execution will show this error if you skip its previous command. For example, mysql_use_result( ) is a command that needs to be put in between the commands that return data. If you skip this command, it will give you the out-of-sync error that is also one of the common errors in MySQL.

9. Ignoring User

It can be identified as below.

Found the wrong password for user: ‘some_user@some_host’; ignoring user

It mainly occurs due to the wrong password entered in any entry in the user table. If mysqld finds such an entry on its startup or when reloading the permission, you will be shown this error. The other reasons due to which this error can pop up are mentioned below.

  • If there is a mismatch between the versions of the user table and mysqld, then this error can be generated. A newer version of the MySQL database will not work with the older user table version. It can be verified by mysqlshow mysql user to view if the password limit is less than 16 characters.
  • If you are having an old password and you forgot to start the database with the –old-protocol command.

10. Table ‘name’ Does Not Exist Error

The list of common errors in MySQL has included this error as it occurs more often than any other error. It is displayed in two ways, viz. Table ‘name’ doesn’t exist and Can’t find file: ‘name’ (errno: 2). 

If a user has to see this error, it means that there is no table with the title ‘name’ in the current database. Sometimes, it happens that the table is present in the MySQL database, but the user is naming it incorrectly, leading to this error. It is a common fault as sqld saves the table in directories and files and even is case sensitive.

An easy SHOW TABLES query can be used to determine which tables are present currently in the MySQL database.

11. File Not Found

To specify or find a particular file in the MySQL database, you need to allocate enough descriptors so that MySQL can find them. This error usually occurs with the error number 23 or 24 in the form of errno 23 and errno 24.

The 1024 error in MySQL is also one of the common errors in MySQL that can be identified if you see any of the following.

ERROR ‘…’ not found (errno: 23)

Can’t open file: … (errno: 24)

The perror utility is a resolve to identify the cause of the error number in sqld.

shell> perror 23

File table overflow

shell> perror 24

Too many open files

shell> perror 11

Resource temporarily unavailable

Here, it can be gathered that the database is trying to open or keep in memory several files at once.

These are the top 11 common errors in MySQL that are faced by users. You can try to use the above-mentioned commands to tackle them. Perhaps, it is quite a tricky process, and a movie user cannot execute it efficiently.

Hence, to overcome all these constraints, you can directly go for an alternate solution, i.e. MySQL Database Recovery Tool. It is the finest utility to repair and recover MySQL database files effortlessly. Moreover, you can extract all the data from the database files.

Conclusion

We have outlined for you the top 11 common errors in MySQL that users face constantly. Knowing the MySQL error log in detail will help you to avoid them and thereby increase your MySQL error handling. A professional third-party tool is suggested to resolve any error by recovering and repairing the MySQL database file. Furthermore, you can save the recovered SQL database to a new script with this tool without any hassle.