Error establishing a database connection Recurring - mysql

My server keep reporting this error.
I think there is something wrong with the mySQL server.
Every time I go into it and restart it and log in with:
mysqld_safe --skip-grant-tables &
My site works again temporarily but then reverts back to
Error establishing a database connection

It is probable that your server is running out of memory, I would suggest creating a Swapfile. You can read how to do this in https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04

Related

Digital ocean sql connection and phpmyadmin suddenly stopped working

I have a Laravel app on digital ocean and it runned fine for about 4 days now.
But today when I woke up it suddenly couldn't connect to the DB.
Also when I try to login in phpmyadmin it says
2002 - Connection refused — The server is not responding (or the local server's socket is not correctly configured).
I tried changing localhost to 127.0.0.1 in the config-db.php file and restarting apache, because some guy in their forums had the same problem and said that it fixed it for him, but for me it had no effect.
Other errors I see are
mysqli_real_connect(): (HY000/2002): Connection refused
Connection for controluser as defined in your configuration failed.
mysqli_real_connect(): (HY000/2002): Connection refused
I am certain that no configuration files have been changed, it just stopped working, why that might be, and how to prevent it in the future ?
The OS is Ubutnu 18.04.13 (if it matters)
It would appear as if your MySQL daemon is no longer running.
The hints here are that the Laravel app is not able to reach the MySQL server, and that phpMyAdmin is also unable to reach the MySQL server.
You should look in the MySQL error log for hints. You may also find hints in your syslog, depending on how your system is configured. This could give you information about why the service has stopped. You might also find information in the systemd log, which can probably best be viewed with journalctl -u mysql -b.
You could verify that it's actually stopped with systemctl status mysql, even though it's difficult for me to think of a reason why it would be running correctly but not responding to any connection attempts.
Next, you should probably start the service again with sudo systemctl start mysql. If it fails to start, you'll see some information about why not with information about viewing the log file, which you can copy and paste in to your question to help us further with troubleshooting.

MySQL server has gone away after Shutdown and Startup Server

I am using MySQL Workbench. I shut down and restart my server. After that I was not able to execute any queries as the error always come up immediately.
Error 2006:MySQL server has gone away
I have started the MySQL57 services manually so I am sure the server is running. Looking up SO, two solutions come up - (1) set max_allowed_packet = 128M in my.ini [Failed], (2) set wait_timeout to a larger number - I cannot find the my.cnf file so this doesn't work.
What I encountered is pretty different from others as they usually had this error after a long piece of queries, but mine just comes up immediately after a query is sent. Appreciate any help (include finding the my.cnf file).
Update:
Discovered something that may help, what I have done:
Start MySQL57 from services.msc manually
Open MySQL Workbench, connect to database
Test the connection, and said "Successfully made the MySQL Connection"
Run a query, return "Error 2013: Cannot connect to MySQL Server on local host"
Run the query again, return "Error 2006: MySQL Server has gone away"
Check services.msc, the MySQL57 has been switched off.

MySQL localhost: "connection refused"

sorry for this post that it might be repeated, but I could not quite figure out from the other posts still.
I am unable to log on mysql localhost database, and the server is down says mysql#localhost:3366 - Refusing Connections. In mysql workbench start/shutdown mysql server, it is saying the database server instance is unknown (with start server button grayed out) and refreshing the status doesn't help.
Also, the mysql server should always be running automatically in the background whenever PC is restarted, but it is not showing in the services now.
when I try to execute mysqld from cmd, it just shuts down the server. And responds with
-"The Innodb memory heap is disabled"
-"the system tablespace must be writeable"
-"InnoDB init function returned error"
-"InnoDB registration as a storage engine failed"
Anybody has a solution to this? Thanks much!
Install it. Re-install it, if you're convinced it was already installed. The fact that it isn't even listed in the services suggests otherwise however. If it was installed but wouldn't start it would still show up, but not as started.

Mysql not generating log when connection fails

I am continuously getting below error while connecting to mysql-
Can\'t connect to MySQL server on /ip/address
but mysql is not generating any log for this error. I have below entries in my.cnf file
log=/var/log/mysql_err.log
log-error=/var/log/mysql/mysql_error.log
I am using correct credentials. No issue of conections.
Now how will I determine the exact issue If I'll not get any log ?
Any Idea, how to solve this ?
This is not surprising:
the server can only log an incident it is aware of. However your client does not even reach the server at all! So how should the server know some client has attempted to contact it?
The error message you get clearly indicates that you do have a connection issue.
You can easily make a test to check the most common problems: just open a telnet connection from the system trying to connect to the system the sql server runs on, connect to the mysql port: telnet <ip-of-mysql-server> mysql
On typical unixoid systems "mysql" will be substituted by the "well known port number of mysql, which is 3306. otherwise you have to specify it manually. Do you get a connection at all? I would guess not. This means either the mysql server is not listening where expected (not running or configured otherwise) or the connection is blocked on network level (firewall).

ERROR 2013 (HY000): Lost connection to MySQL server at 'reading authorization packet', system error: 0

I am getting the following error
ERROR 2013 (HY000): Lost connection to MySQL server at
'reading authorization packet', system error: 0
when trying to connect to my MySQL server.
What I am doing:
I have Master - Slave replication in MySQL that is working and just added load balance capabilities using F5.
I have configured the F5 according to their site.
But when I am trying to connect to my MySQL server using the IP that the F5 was configured with I get
ERROR 2013 (HY000): Lost connection to MySQL server at
'reading authorization packet', system error: 0
Any ideas?
Update on my progress : ZERO
- i am getting the same error
I get no entries in the /var/log/secure as if somebody would try to authenticate coming form the ip where i had created my load balance server.
No enties in the mysql error log.
The command - returns nothing
mysql> SHOW GLOBAL STATUS LIKE 'Aborted_connections';
Empty set (0.00 sec)
I've already altered my my.cnf file and add the
[mysqld]
skip-name-resolve
Alterd the connect_timeout to 10.
So it seems i get no response for the server i have created on my F5
I finally convinced the F5 admin to pass me the log for the F5 server and i have exctraced all i need form it.
Here is the output :
Jan 28 15:46:39 tmm debug tmm[6459]: Rule /Common/iRule-f5_mysql_proxy <CLIENT_ACCEPTED>: BIG-IP MySQL Proxy -- clientside initial connection
Jan 28 15:46:39 tmm debug tmm[6459]: Rule /Common/iRule-f5_mysql_proxy <CLIENT_ACCEPTED>: BIG-IP MySQL Proxy -- clientside responding with server WELCOME packet
Jan 28 15:46:39 tmm debug tmm[6459]: Rule /Common/iRule-f5_mysql_proxy <CLIENT_DATA>: BIG-IP MySQL Proxy -- clientside authenticated flag not set
Jan 28 15:46:39 tmm err tmm[6459]: Rule /Common/iRule-f5_mysql_proxy <CLIENT_DATA>: BIG-IP MySQL Proxy -- mysql client: attempting to do something before authentication
Jan 28 15:46:39 tmm debug tmm[6459]: Rule /Common/iRule-f5_mysql_proxy <LB_SELECTED>: BIG-IP MySQL Proxy -- serverside selected pool /Common/foss-mysql-slave_pool node SLAVE-IP
Jan 28 15:46:39 tmm debug tmm[6459]: Rule /Common/iRule-f5_mysql_proxy <CLIENT_CLOSED>: BIG-IP MySQL Proxy -- clientside connection closed from MASTER-IP(XXXXXXX)
Jan 28 15:46:39 tmm debug tmm[6459]: Rule /Common/iRule-f5_mysql_proxy <SERVER_CLOSED>: BIG-IP MySQL Proxy -- serverside connection closed from node SLAVE-IP(XXXXXXXX)
I've replaced the ip for security sake !
just as an extra - and i think is here the problem - my mysql version is 5.1.69-log
Thx All
From documentation:
More rarely, it can happen when the client is attempting the initial
connection to the server. In this case, if your connect_timeout value
is set to only a few seconds, you may be able to resolve the problem
by increasing it to ten seconds, perhaps more if you have a very long
distance or slow connection. You can determine whether you are
experiencing this more uncommon cause by using SHOW STATUS LIKE
'aborted_connections'. It will increase by one for each initial
connection attempt that the server aborts. You may see “reading
authorization packet” as part of the error message; if so, that also
suggests that this is the solution that you need.
Try increasing connect_timeout in your my.cnf file
Another style:
MySQL: Lost connection to MySQL server at 'reading initial communication packet'
At some point, it was impossible for remote clients to connect to
the MySQL server.
The client (some application on a Windows platform) gave a vague
description like Connection unexpectedly terminated.
When remotely logging in with the MySQL client the following error
appeared:
ERROR 2013 (HY000): Lost connection to MySQL server at 'reading initial communication packet', system error: 0
On FreeBSD this happens because there was no match found in /etc/hosts.allow. Adding the following line before the line saying ALL:ALL fixes this:
mysqld: ALL: allow
On non-FreeBSD Unix systems, it is worth to check the files /etc/hosts.allow and /etc/hosts.deny. If you are restricting connections, make sure this line is in /etc/hosts.allow:
mysqld: ALL
or check if the host is listed in /etc/hosts.deny.
In Arch Linux, a similar line can be added to /etc/hosts.allow:
mysqld: ALL
This is usually caused by an aborted connect. You can verify this by checking the status:
mysql> SHOW GLOBAL STATUS LIKE 'Aborted_connects';
If this counter keeps increasing as you get the lost connections, that's a sign you're having a problem during connect.
One remedy that seems to work in many cases is to increase the timeout. A suggested value is 10 seconds:
mysql> SET GLOBAL connect_timeout = 10;
Another common cause of connect timeouts is the reverse-DNS lookup that is necessary when authenticating clients. It is recommended to run MySQL with the config variable in my.cnf:
[mysqld]
skip-name-resolve
This means that your GRANT statements need to be based on IP address rather than hostname.
I also found this report from 2012 at the f5.com site (now protected by login, but I got it through Google cache)
It is likely the proxy will not work unless you are running BIG-IP 11.1 and MySQL 5.1, which were the versions I tested against. The MySQL protocol has a habit of changing.
I suggest you contact F5 Support and confirm that you are using a supported combination of versions.
I've struggled a lot with this error. Tried every single answer I found on the internet.
In the end, I've connected my computer to my cell phone's hotspot and everything worked. I turned out that my company's internet was blocking the connection with MySQL.
This is not a complete solution, but maybe someone faces the same problem. It worths to check the connection.
I solved this by stopping mysql several times.
$ mysql.server stop
Shutting down MySQL
.. ERROR! The server quit without updating PID file (/usr/local/var/mysql/xxx.local.pid).
$ mysql.server stop
Shutting down MySQL
.. SUCCESS!
$ mysql.server stop
ERROR! MySQL server PID file could not be found! (note: this is good)
$ mysql.server start
All good from here. I suspect mysql had been started more than once.
My case was that the server didn't accept the connection from this IP. The server is a SQL server from Google Apps Engine, and you have to configure allowed remote hosts that can connect to the server.
Adding the (new) host to the GAE admin page solved the issue.
I have a mac but would assume all linux are the same for this part...
In my case I got this:
2018-12-03 11:13:27 - Start server:
2018-12-03 11:13:27 - Server start done.
2018-12-03 11:13:27 - Checking server status...
2018-12-03 11:13:27 - Trying to connect to MySQL...
2018-12-03 11:13:27 - Lost connection to MySQL server at 'reading authorization packet', system error: 0 (2013)
2018-12-03 11:13:27 - Assuming server is not running
I ran this:
sudo killall mysqld
And then started the mysql again through mysqlworkbench although in your case it might be like this:
mysql.server start
*sidenote: I tried running mysql.server stop and got this Shutting down MySQL
.... SUCCESS! but after running ps aux | grep mysql I saw that it hasn't really shut down...
I use several mysql connections (connecting to different sets of databases) in localhost.
This happened to me after I shut my computer down and mysql was not properly shutdown. After starting my machine I was able to successfully connect to multiple db connections except one (I used this a lot before my machine shutdown).
As per the instructions in this posts I doubled connect_timeout but I was not able to connect to that one database connection.
I restarted my machine and i can successfully connect now. This will help you unblock yourself but it'd be great if it can be fixed without restarting the machine.
Another concern is: connection_timeout seemed to me delay related problem but I was getting the error immediately in localhost when there is no network in the equation.
In my case, it happened when there were a lot of connection to the MySQL server (15,000 connections) and the free memory was about 120M . After I added more memory to the server, the error was gone.
I scratched my head about this error for 3 days. I tried tweaking permissions on the database, new users from different IPs in the Users table, adjusting the bind-address in a bunch of different ways, comparing my my.cnf file to a known working server, firewall changes, upstream firewall changes, hosts.allow/deny...none of them worked.
Then I looked not at mysql/error.log (which came up empty) but my journalctl -xe log and low and behold, it couldn't read my /etc/hosts.allow and my /etc/hosts.deny file.
chmod 644 hosts.allow
chmod 644 hosts.deny.
All better now.
Another possibility can be connection reset from the TCP wrappers (/etc/hosts.deny and /etc/hosts.allow). Just check what is coming in from the telnet to port 3306 - if it is nothing, then there is something is in the middle preventing communication from happening.
I've created my account just to add this bit of information to this old question, because nowhere on the web I found any reference to the cause of my problem which I eventually found.
(Adding it here cause this is the top google result, also when adding PHP as search term)
In PHP 7.4 when you fork a process (I know, who does this??) that has an active MySQL connection, the connection will get messed up and spit out the OP's error.
just reinitialize/recreate the connection in each forked process after the forking, this will fix it.
Hope it this helps anybody.
I got both errors: mostly reading initial communication packet and reading authorization packet one time. It seems random, but sometimes I was able to establish a connection after reboots, but after some time the error creeped back.
Avoiding the 5GHz WiFi in the client seems to have fixed the issue. That's what worked for me (server was always connected to 2.4GHz).
I tried everything from server versions, odbc connector versions, firewall settings, installing some windows update (and then uninstalling them), some of the answers posted here, etc... lost my entire sleep time for today. Super tired day awaits me.
If you get this when using DevDesktop - just restart DevDesktop!