Ошибка cannot connect to database

I also struggled with this problem for quite a while.

I came accross this interesting thread from MySQL forum: http://forums.mysql.com/read.php?11,11388,11388#msg-11388

I also came accross (obviously) some good SO Q/A.

It seems that the message mentioned in «user948950» ‘s question can be coming from a wide range of reasons: log file too big, incorrect mysql.ini file values, spaces in the file path, security/acl issue, old entries in the registry, and so on.

So, after trying for 3h to fix this… I abandonned and decided to do a good old re-install.

This is where this post from (again) this MySQL thread came in useful, I quote:

Gary Williams wrote: Hi Guys,

I’ve had exactly the same problem and this is how I got it working
for me, starting with a non working installation.

1. Stop the windows service for any existing mysql installation.

2. Uninstall Mysql.

As with most uninstalls, old files are left behind. If your directory
is C:mysql etc then delete the innob, etc, files but leave the
directories themselves as well as any existing databases in ‘data’.
If your directory is C:Program Files etc, delete all the mysql
directories.

1. It’s now worth running regedit to make sure the old registry entries are deleted as well by the uninstall. If not, delete them.

2. It’s ok to use the new .msi installer (essential files only), however ….

3. Do not use their default install path! Some genius set a path with spaces in it! Choose the custom install and select a sensible path,
   ie, C:mysql (note from Adrien: C:mysqldata for … the data)

4. Do not choose to alter the security settings. Uncheck the relevant box and the install will complete without having to set a root
   password.

I think I have remembered everything.

Good luck

Gary

I did get into troubles when simply copy/pasting the databases I had in my previous «data» directory to the new one. So the work around I found was to export each database (I know… a lot of fun) and then re-import them one by one.

FYI: I used the following command to import C:/<MySQLInstallDir>/My SQL Server x.x/bin/mysql -u root -p <dbName> < "<dirPathOfDump><dumpName>.sql", that is for instance C:/mysql/MySQL Server 5.6/bin/mysql -u root -p mySupaCoolDb < "C:mySupaCoolDbDump20130901.sql"

Are you looking for a solution to “zabbix cannot connect to the database” error ? Here’s how we fix it.

Zabbix is a monitoring software tool. When using zabbix we may encounter many errors like zabbix cannot connect to the database. This may occur due to incorrect database details.

At Bobcares, we often get requests from our customers to fix ‘zabbix cannot connect to the database’ as part of our Server Management Services.

Today, we’ll see the reasons and how our Support Engineers fix this error.

Causes for ‘Zabbix cannot connect to the database’ Error

At Bobcares, where we have more than a decade of expertise in managing servers, we see many customers face problems while managing Zabbix.

Now, let’s see the major reasons for this Zabbix error to occur and we’ll also see how our Support Engineers fix this zabbix database cannot connect error.

Incorrect Database details

Recently one of our customers approached us with the same zabbix problem. He said he was getting an error in his zabbix dashboard like the one shown below in the screenshot.

When we checked in detail, our Support Engineers found that there is mismatch in the details given in database with those in zabbix_server configuration file.

We found that the DBName given in database was not the same as the one given in zabbix configuration file. So, we changed it to the right one. Finally, this fixed the error.

We also Checked and confirmed whether all other values entered were right.

Incorrect DBsocket

We got another request from some other customer. However, the error was similar. Here is the error message our customer was receiving.

[ZXXX] connection to database 'Databasename' failed: [2002] Can't connect to local MySQL server through socket '/var/lib/mysql'

We checked and found that the socket given in mysql configuration file is different from the one specified in the configuration file for zabbix. In mysql configuration DBSocket value was  /var/run/mysql/mysql.sock and in zabbix_server configuration it was  DBSocket=/var/run/mysql. So, we made the following corrections in zabbix configuration file:

XXXX:/usr/share/zabbix # cat /etc/zabbix/zabbix-server.conf
LogFile=/var/log/zabbix/zabbix-server.log
PidFile=/var/run/zabbix/zabbix-server.pid
DBName=*****
DBUser=*****
DBPassword=*************
DBSocket=/var/run/mysql/mysql.sock

And this fixed the problem.

[Need any further assistance in fixing zabbix errors? – We’ll help you]

Conclusion

In short, ‘Zabbix cannot connect to the database’ error may occur due to some reasons like wrong database details or when there is any mismatch in configuration file values, etc. Today, we saw how our Support Engineers fix this error.

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The Problem

SharePoint Products Configuration Wizard, when run for the first time, will create the Configuration DB and create a new SharePoint farm. In higher environment other than Dev it is a mandated practice to maintain two separate servers for application and
database. SharePoint Products Configuration Wizard will be run in the application server where SharePoint is installed. In the configuration wizard, we will be specifying the back-end database where configuration database has to be created. So there would
be a continuous network traffic exchange between the Application Server and the back-end Database Server when the Configuration wizard is run. When the Configuration Wizard runs for the first time there can be a chance that the below error pops up intermittently.

In this article, we will see how we can overcome the issue.

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How it happens

During the SharePoint Installation time, Run the SharePoint Products Configuration Wizard and click Next.

Click Yes to continue.

We are setting up a new farm, hence select the radio button ‘Create a new server farm’ and click Next.

Specify the database server name (VM02-SQL2016 in our case) in the field ‘Database Server’. The database access account used for the configuration will be ‘SPFarmAccount’ which will act as the farm account which is present in the domain.  Click
Next.

However, we may run into the problem which is shown below.

On checking the SQL Server for the account permissions for SPSetupAccount(the account used for installing SharePoint), it was having ‘DBCreator’ and ‘Security Admin’ Privileges as mandated. As per the requirement, ‘SPFarmAccount’
(Farm Account) just needs to be a domain user. During the time of Configuration, the installer will automatically grant
SPFarmAccount with DBOwner and SecurityAdmin privileges in the SQL Server. We don’t have to explicitly grant anything for
SPFarmAccount.

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Root Cause & Resolution

After a lot of digging the root cause seems to be that SQL Server was not allowing any incoming connections. So we will have to enable it. Let’s see how to do it.

Go to the SQL Server VM and spin up SQL Server 2016 Configuration Manager.

Select SQL Server Network Configuration and click Protocols for MSSQLSERVER. TCP/IP is disabled by default. Enable it.

After doing that we have to write a firewall rule that will enable incoming connections to 1433 port which is where SQL Server listens to. Go to Control Panel -> System and Security -> Windows Firewall. Select Advanced Settings option.

Click ‘Inbound Rules’ and select ‘New Rule’ option.

This will open up the inbound rule configuration wizard. Select the radio button ‘Port’ and click Next.

Select the TCP radio button and specify the port 1433 in specific local ports text box.

Specify the action that has to be taken as part of the rule, select ‘Allow the connection’ radio button.

In profiles page, select the check box ‘Domain’ and click Next.

Specify the name for the rule and click Finish.

Make sure that you restart the SQL Server service for the changes to take effect.

Now if we go back to the Configuration Wizard in the SharePoint VM and click Next, it will proceed to the next page without any exception. 

Thus we saw how to resolve the ‘Cannot connect to database master at SQL Server’ error that occurs during the installation of SharePoint Server 2016.

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See Also

This article can also be viewed at the below link :

• Resolving ‘Cannot Connect To DataBase Master At SQL Server’ Error During SharePoint 2016 Installation