mysql - How to change max_allowed_packet size

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I am having a problem with BLOB fields in my MySQL database - when uploading files larger than approx 1MB I get an error Packets larger than max_allowed_packet are not allowed.

Here is what i've tried:

In MySQL Query Browser I ran a show variables like 'max_allowed_packet' which gave me 1048576.

Then I execute the query set global max_allowed_packet=33554432 followed by show variables like 'max_allowed_packet' - it gives me 33554432 as expected.

But when I restart the MySQL server it magically goes back to 1048576. What am I doing wrong here?

Bonus question, is it possible to compress a BLOB field?

A BLOB field is a Binary Large OBject. It's just bits. So yes, you can compress the contents, and it gives other (and hopefully, less) bits you store in the BLOB-field instead. It just changes which data you put in it. You'll have to decompress the BLOB-contents when you need it again, too. – Konerak Nov 9, 2011 at 9:12 possible duplicate of MySQL Error 1153 - Got a packet bigger than 'max_allowed_packet' bytes – cnst Jan 17, 2014 at 4:04

Change in the my.ini or ~/.my.cnf file by including the single line under [mysqld] or [client] section in your file:

max_allowed_packet=500M
then restart the MySQL service and you are done.
See the documentation for further information.
                Thanks seems to be working even though I had hoped this would be possible without having to modify ini files manually.
– Muleskinner
                Nov 9, 2011 at 9:24
                It seems rather pointless to give someone an answer and then tell them they should go check Google for an answer. Especially since, SO is invariably occupies several of the top results for any decent programming related question. Talk about programming an infinite loop!!! Google > SO > Google > SO > Google > SO and so on.
– Phill Healey
                Feb 19, 2016 at 11:06
                Make sure it is under [mysqld] and not [mysql] (very similar). Cost me some minutes of headscratching.
– Halvor Holsten Strand
                Dec 15, 2016 at 8:26
The max_allowed_packet variable can be set globally by running a query.
However, if you do not change it in the my.ini file (as dragon112 suggested), the value will reset when the server restarts, even if you set it globally.
To change the max allowed packet for everyone to 1GB until the server restarts:
SET GLOBAL max_allowed_packet=1073741824;
                @artnikpro It does work, "Query OK, 0 rows affected (0.00 sec)" might feel misleading but it is right.
– AnnTea
                Aug 4, 2014 at 12:09
                doesn't work for me. SHOW VARIABLES WHERE variable_name = 'max_allowed_packet' still shows old value
– Poma
                May 22, 2015 at 22:47
                It shows the old value because max_allowed_packet doesn't change for existing connections.  If you disconnect and reconnect you'll see the updated value.
– Matt Wonlaw
                Jul 29, 2015 at 20:51
One of my junior developers was having a problem modifying this for me so I thought I would expand this in greater detail for linux users:
open terminal
ssh root@YOURIP
enter root password
nano /etc/mysql/my.cnf  (if command is not recognized do this first or try vi then repeat: yum install nano )
add the line: max_allowed_packet=256M (obviously adjust size for whatever you need) under the [MYSQLD] section. He made a mistake of putting it at the bottom of the file first so it did not work.
Control + O (save)  then Enter (confirm) then Control + X (exit file)
service mysqld restart
You can check the change in the variables section on phpmyadmin
                this was actually done on CentosOS6 , I of course agree about not using root ssh access though
– naw103
                Jun 16, 2015 at 0:38
                @tamasd A few GNU/Linux distros that I've used (like Debian 8 and CentOS 6) produce sudo: command not found or this incident will be reported because either sudo has not been installed and configured. Would it be better to litter this answer with instructions on setting up sudo for the first time?
– Damian Yerrick
                Sep 15, 2016 at 16:38
                not root ssh is the problem, but password login is. A user account with sudo permission is almost as unsecure as root is. Just use SSH key based authentication.
– Martin Schneider
                Mar 1, 2017 at 21:43
                the matter of how to log into the machine is OT, he rightly reported in his recipe that you have to log in, in a way or another.
– devsmt
                Feb 1, 2018 at 8:15
I think some would also want to know how to find the my.ini file on your PC. For windows users, I think the best way is as follows:
Win+R(shortcut for 'run'), type services.msc, Enter
You could find an entry like 'MySQL56', right click on it, select properties
You could see sth like "D:/Program Files/MySQL/MySQL Server 5.6/bin\mysqld" --defaults-file="D:\ProgramData\MySQL\MySQL Server 5.6\my.ini" MySQL56
I got this answer from http://bugs.mysql.com/bug.php?id=68516
                This is important on Windows. Had MySQL as a service and edited my.ini in Workbench and this answer made me realize that MySQL as a service uses an other my.ini then the one i edited in Workbench.
– Robert Niestroj
                Jan 25, 2019 at 9:04
Following all instructions, this is what I did and worked:
mysql> SELECT CONNECTION_ID();//This is my ID for this session.
+-----------------+
| CONNECTION_ID() |
+-----------------+
|              20 |
+-----------------+
1 row in set (0.00 sec)
mysql> select @max_allowed_packet //Mysql do not found @max_allowed_packet
+---------------------+
| @max_allowed_packet |
+---------------------+
| NULL                |
+---------------------+
1 row in set (0.00 sec)
mysql> Select @@global.max_allowed_packet; //That is better... I have max_allowed_packet=32M inside my.ini
+-----------------------------+
| @@global.max_allowed_packet |
+-----------------------------+
|                    33554432 |
+-----------------------------+
1 row in set (0.00 sec)
mysql> **SET GLOBAL max_allowed_packet=1073741824**; //Now I'm changing the value.
Query OK, 0 rows affected (0.00 sec)
mysql> select @max_allowed_packet; //Mysql not found @max_allowed_packet
+---------------------+
| @max_allowed_packet |
+---------------------+
| NULL                |
+---------------------+
1 row in set (0.00 sec)
mysql> Select @@global.max_allowed_packet;//The new value. And I still have max_allowed_packet=32M inisde my.ini
+-----------------------------+
| @@global.max_allowed_packet |
+-----------------------------+
|                  1073741824 |
+-----------------------------+
1 row in set (0.00 sec)
So, as we can see, the max_allowed_packet has been changed outside from my.ini.
Lets leave the session and check again: 
mysql> exit
C:\Windows\System32>mysql -uroot -pPassword
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 21
Server version: 5.6.26-log MySQL Community Server (GPL)
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> SELECT CONNECTION_ID();//This is my ID for this session.
+-----------------+
| CONNECTION_ID() |
+-----------------+
|              21 |
+-----------------+
1 row in set (0.00 sec)
mysql> Select @@global.max_allowed_packet;//The new value still here and And I still have max_allowed_packet=32M inisde my.ini
+-----------------------------+
| @@global.max_allowed_packet |
+-----------------------------+
|                  1073741824 |
+-----------------------------+
1 row in set (0.00 sec)
Now I will stop the server
2016-02-03 10:28:30 - Server is stopped
mysql> SELECT CONNECTION_ID();
ERROR 2013 (HY000): Lost connection to MySQL server during query
Now I will start the server
2016-02-03 10:31:54 - Server is running
C:\Windows\System32>mysql -uroot -pPassword
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 5.6.26-log MySQL Community Server (GPL)
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> SELECT CONNECTION_ID();
+-----------------+
| CONNECTION_ID() |
+-----------------+
|               9 |
+-----------------+
1 row in set (0.00 sec)
mysql> Select @@global.max_allowed_packet;//The previous new value has gone. Now I see what I have inside my.ini again.
+-----------------------------+
| @@global.max_allowed_packet |
+-----------------------------+
|                    33554432 |
+-----------------------------+
1 row in set (0.00 sec)
Conclusion, after SET GLOBAL max_allowed_packet=1073741824, the server will have the new max_allowed_packet until it is restarted, as someone stated previously.
                if **SET GLOBAL max_allowed_packet=1073741824**; generates error, you can try after removing ** symbol. i.e. SET GLOBAL max_allowed_packet=1073741824;
– Rahul Vansh
                Apr 1 at 7:45
If getting this error while performing a backup, max_allowed_packet can be set in the my.cnf particularly for mysqldump.
[mysqldump]
max_allowed_packet=512M
I kept getting this error while performing a mysqldump and I did not understand because I had this set in my.cnf under the [mysqld] section. Once I figured out I could set it for [mysqldump] and I set the value, my backups completed without issue.
socket      = /tmp/mysql.sock
key_buffer_size = 16M
max_allowed_packet = 16M        // --> changing this wont solve
sort_buffer_size = 512K
Scroll down to the end until u find
[mysqld]
port=3306
explicit_defaults_for_timestamp = TRUE
Add the line of packet_size in between
[mysqld]
port=3306
max_allowed_packet = 16M
explicit_defaults_for_timestamp = TRUE
Check whether it worked with this query
Select @@global.max_allowed_packet;
This error come because of your data contain larger then set value.
Just write down the max_allowed_packed=500M
or you can calculate that 500*1024k and use that instead of 500M if you want.
Now just restart the MySQL.
For anyone running MySQL on Amazon RDS service, this change is done via parameter groups. You need to create a new PG or use an existing one (other than the default, which is read-only).
You should search for the max_allowed_packet parameter, change its value, and then hit save.
Back in your MySQL instance, if you created a new PG, you should attach the PG to your instance (you may need a reboot). 
If you changed a PG that was already attached to your instance, changes will be applied without reboot, to all your instances that have that PG attached.
Many of the answerers spotted the issue and already gave the solution.
I just want to suggest another solution, which is changing the Glogal variable value from within the tool Mysql Workbench. That is ofcourse IF you use Workbench running locally on server (or via SSH connection)
You just connect to your instance and go on menu:
  Server -> Options File -> Networking -> max_allowed_packed
You set the desired value and then you need to restart MySql Service.