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What do I do if I fail to connect to an ApsaraDB RDS instance?

Last Updated: Aug 05, 2022

This topic describes how to resolve various issues that cause failures to connect to an ApsaraDB RDS instance.

Issues that cause failures to connect an ECS instance to an RDS instance over an internal network

You can connect an Elastic Compute Service (ECS) instance to an RDS instance over an internal network only when these instances reside in the same region. These instances can reside in the same zone or different zones of the same region.

  • Make sure that the ECS instance and the RDS instance reside in the same region.

    • View the region in which the ECS instance resides. 1

    • View the region in which the RDS instance resides. 2

  • If the ECS instance and the RDS instance reside in different regions, these instances cannot directly communicate with each other over an internal network. In this case, you can use one of the following methods to resolve the issue:

    • Method 1: Release or unsubscribe from the ECS instance or the RDS instance. Then, purchase an ECS instance or an RDS instance that resides in the specified region.

    • Method 2: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. For more information about how to apply for a public endpoint for an RDS instance, see Apply for or release a public endpoint for an ApsaraDB RDS for MySQL instance. This method cannot ensure optimal performance, security, or stability.

Check network types

  1. Make sure that the ECS instance and the RDS instance both reside in virtual private clouds (VPCs) or in the classic network.

    • View the network type of the ECS instance. 3

    • View the network type of the RDS instance. 4

  2. If one instance resides in the classic network and the other instance resides in a VPC, use one of the following methods to resolve the issue:

    • Methods suitable in scenarios in which the ECS instance resides in a VPC and the RDS instance resides in the classic network:

      • Method 1: This is the recommended method. Change the network type of the RDS instance from the classic network to a VPC. During the configuration process, select the VPC to which the ECS instance belongs. For more information, see

        Switch the network type.

      • Method 2: Purchase an ECS instance that resides in the classic network. Take note that a VPC provides higher security than the classic network. We recommend that you use VPCs.

        Note

        ECS instances cannot be migrated from VPCs to the classic network.

      • Method 3: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. For more information about how to apply for a public endpoint for an RDS instance, see Apply for or release a public endpoint for an ApsaraDB RDS for MySQL instance. This method cannot ensure optimal performance, security, or stability.

    • Methods suitable in scenarios in which the ECS instance resides in the classic network and the RDS instance resides in a VPC:

      • Method 1: This is the recommended method. Change the network type of the ECS instance from the classic network to a VPC. During the configuration process, select the VPC to which the RDS instance belongs. For more information, see Migrate an ECS instance from a classic network to a VPC.

      • Method 2: Change the network type of the RDS instance from a VPC to the classic network. Take note that a VPC provides higher security than the classic network. We recommend that you use VPCs.

      • Method 3: Use the ClassicLink feature to establish an internal network connection between the classic network-type ECS instance and the VPC-type RDS instance. For more information about the ClassicLink feature, see Enable ClassicLink.

        Note

        If the internal network connection between classic network-type ECS instance and the VPC-type RDS instance cannot be established after the ClassicLink feature is used, handle the issue based on the descriptions in Troubleshoot connection issues between a classic network and a VPC after you establish a ClassicLink connection.

      • Method 4: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. For more information about how to apply for a public endpoint for an RDS instance, see Apply for or release a public endpoint for an ApsaraDB RDS for MySQL instance. This method cannot ensure optimal performance, security, or stability.

  3. If the ECS instance and the RDS instance both reside in VPCs, make sure that these instances reside in the same VPC.

    • View the VPC ID of the ECS instance. 5

    • View the network type of the RDS instance. 6

  4. If the ECS instance and the RDS instance reside in different VPCs, use one of the following methods to resolve the issue:

  5. If the ECS instance and the RDS instance reside in the same VPC and in the same region, the ECS instance can connect to the RDS instance by using the public endpoint rather than the internal endpoint of the RDS instance, and both the ping and telnet commands return connection failures, you can resolve the issue based on the descriptions in What do I do if an ECS instance cannot connect to an ApsaraDB RDS instance due to routing problems?

Issues that cause failures to connect to an RDS instance over the internal network

Make sure that the public endpoint of the RDS instance is used to connect to the RDS instance. You can view the public endpoint of the RDS instance on the Database Connection page in the ApsaraDB RDS console.

7

Make sure that the IP address of the on-premises device that you want to connect to the RDS instance is added to an IP address allowlist of the RDS instance. If the on-premises device can be connected to the RDS instance after 0.0.0.0/0 is added to the IP address allowlist of the RDS instance, the IP address of the on-premises device is not granted access to the RDS instance. In this case, you can add the IP address of the on-premises device to an IP address allowlist of the RDS instance. For more information about how to configure an IP address allowlist for an RDS instance, see Configure an IP address allowlist for an ApsaraDB RDS instance. For more information about how to obtain the IP address of an on-premises device, see the following topics:

Common connection errors

The following table describes common connection errors and the solutions to these errors.

Database type

Error message

Cause

Solution

MySQL or MariaDB TX

  • ERROR 2003 (HY000): Can't connect to MySQL server on 'XXX'(10038, 10060, or 110)

  • Cannot connect to a database: XXX

Network communication is abnormal.

  • Make sure that the ECS instance and the RDS instance reside in the same region.

  • Make sure that the ECS instance and the RDS instance reside in the same type of network.

  • Make sure that the ECS instance and the RDS instance reside in the same VPC.

  • Make sure that the IP address of the ECS instance is added to an IP address allowlist of the RDS instance.

For more information, see Solutions.

  • ERROR 1045 (HY000): #28000ip not in whitelist

  • ERROR 2801 (HY000): #RDS00ip not in whitelist, client ip is XXX

  • ERROR 2013 (HY000): Lost connection to MySQL server at 'reading authorization packet', system error:110

The IP address allowlist of the RDS instance does not contain the IP address from which you want to connect to the RDS instance.

Check the IP address allowlist of the RDS instance

  • ERROR 1045 (28000): Access denied for user 'XXX'@'XXX' (using password: YES or NO)

  • ERROR 1045 (28000): Authentication Failed For RDS maybe username or password is incorrect

The username or password that you entered is invalid.

Check the username and password used to establish a connection between instances

  • ERROR 2005 (HY000): Unknown MySQL server host 'XXX' (110 or 11004)

  • SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

  • Name or service not known

The Domain Name System (DNS) server cannot resolve the endpoint of the RDS instance.

Check whether the endpoint of the RDS instance is correct

SQL Server

Cannot connect to XXX. A network-related or instance-specific error occurred while connecting to SQL Server. The server was not found or was inaccessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.) (Microsoft SQL Server, Error: 10060 or 258)

Network communication is abnormal.

  • Make sure that the ECS instance and the RDS instance reside in the same region.

  • Make sure that the ECS instance and the RDS instance reside in the same type of network.

  • Make sure that the ECS instance and the RDS instance reside in the same VPC.

  • Make sure that the IP address of the ECS instance is added to an IP address allowlist of the RDS instance.

  • Check whether the IP address and port number of the RDS instance are correctly configured for the ECS instance.

For more information, see Solutions.

Cannot connect to XXX.

A connection was successfully established with the server, but an error occurred during the logon process. (provider: TCP Provider, error: 0 - The network name that you specified can no longer be used.) (Microsoft SQL Server, Error: 64)

The IP address allowlist of the RDS instance does not contain the IP address from which you want to connect to the RDS instance.

Check the IP address allowlist of the RDS instance

Logon failed for login 'user' due to trigger execution

The number of connections to the RDS instance reaches the upper limit.

Check whether the number of connections to the RDS instance reaches the upper limit and whether blocked connections exist

cannot open user default database.Login failed

The database to which the specified account logs on by default is deleted. As a result, your logon fails.

Log on to the database by using another account and create a default database for the specified account

PostgreSQL

Unable to connect to server:

could not connect to server: Connection timed out (0x0000274C/10060)Is the server running on host "XXX.rds.aliyuncs.com" and acceptingTCP/IP connections on port XXX?

Network communication is abnormal.

  • Make sure that the IP address of the ECS instance is added to an IP address allowlist of the RDS instance.

  • Check whether the configuration of the allowlist is correct.

  • If you enable the enhanced allowlist mode, check whether the IP address allowlist is added to the required group. For more information, see Enhanced allowlist mode.

For more information, see Solutions.

  • server closed the connection unexpectedly This probably means the server terminated abnormally before or while processing the request.

  • Error connecting to the server: FATAL: no pg_hba.conf entry

The IP address allowlist of the RDS instance does not contain the IP address from which you want to connect to the RDS instance.

Check the IP address allowlist of the RDS instance

FATAL: remaining connection slots are reserved for non-replication superuser connections

The number of connections to the RDS instance reaches the upper limit.

Stop the process for adding connections

FATAL: password authentication failed for user "xxx".

The password is invalid.

Reset the password and try again.

For more information about how to reset a password, see Reset a password.

Connect to an RDS instance by using Data Management (DMS)

The user specified as a definer ('user'@'a.b.c.d') does not exist

The specified account cannot be found. This error may occur only when the database proxy feature is used for the RDS instance. For more information, see ApsaraDB RDS supports the database proxy mode.

Switch from the database proxy mode to the standard mode

The MYSQL server is running with the --rds-deny-access option so it cannot execute this statement

  • The RDS instance expires.

  • The storage capacity of the RDS instance is exhausted.

Renew the RDS instance or upgrade the storage capacity of the RDS instance

You cannot use DMS to connect to the RDS instance.

You are not the owner of the RDS instance, and the owner of the RDS instance has not granted you the logon permissions.

Authorize an Alibaba Cloud account

Check whether the endpoint is valid, the IP address allowlists are correctly configured, and network communication is normal.

In most cases, this error occurs due to the following reasons when you connect a self-managed MySQL database that resides on an ECS instance or an on-premises host to the RDS instance:

  • The firewall of the ECS instance or the firewall of the on-premises host does not allow access from the RDS instance.

  • The security group to which the ECS instance belongs does not allow access from DMS.

  • The self-managed MySQL database is not started.

  • The self-managed MySQL database allows only the logons that you initiate from the ECS instance by using the credentials of the root account.

  • Check the firewall rules of the ECS instance or the on-premises host on which the self-managed MySQL database resides.

  • Add the IP address of DMS servers to the security group of the ECS instance.

  • Use the root account to log on to the MySQL database.

For more information, see Solutions.

max_user_connections

The number of connections to the RDS instance reaches the upper limit.

Solve the issue that the number connections to the RDS instance reaches the upper limit

Cannot log on to the RDS instance due to issues related to the IP address allowlist.

The CIDR blocks of the DMS servers are not added to an IP address allowlist of the RDS instance.

Add the CIDR block of the DMS servers.

References

Applicable scope

  • ApsaraDB RDS