What do I do if I cannot or fail to connect to an ApsaraDB RDS instance that runs MySQL, PostgreSQL, SQL Server, or MariaDB? - ApsaraDB RDS

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

Common connection errors

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

ApsaraDB RDS for SQL Server

Error message	Cause	Solution
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 use the same network type. Make sure that the ECS instance and the RDS instance reside in the same VPC. Make sure that the private IP address of the ECS instance is added to an IP address whitelist of the RDS instance. Check whether the internal endpoint 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 whitelist is not correctly configured.	Check the IP address whitelist 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.

Errors reported when you connect to an RDS instance by using Data Management (DMS)

For more information, see Use DMS to log on to an ApsaraDB RDS for SQL Server instance.

Important

After you reset the password of your account, you must log on to DMS again with the new password.

Error message	Cause	Solution
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
Cannot log on to the RDS instance due to issues related to the IP address whitelist.	The CIDR block of the DMS server is not added to an IP address whitelist of the RDS instance.	Add the CIDR block of the DMS server to an IP address whitelist of the RDS instance.

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

Before you connect an ECS instance to an ApsaraDB RDS instance by using the internal endpoint of the ApsaraDB RDS instance, you must add the private IP address of the ECS instance to an IP address whitelist of the ApsaraDB RDS instance.
Note
- For more information about how to configure an IP address whitelist, see Configure an IP address whitelist for an ApsaraDB RDS for SQL Server instance.
- If you add the public IP address of the ECS instance to an IP address whitelist of the RDS instance, you cannot connect the ECS instance to the RDS instance over an internal network.
You can connect an ECS instance to an RDS instance over an internal network only when the instances reside in the same region. The 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.
  1. View the region in which the ECS instance resides.
  2. View the region in which the RDS instance resides.
- If the ECS instance and the RDS instance reside in different regions, the 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 the ECS instance. Then, purchase an ECS instance that resides in the same region as the RDS instance.
    - Release the RDS instance. Then, purchase an RDS instance that resides in the same region as the ECS instance.
  - Method 2: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. This method delivers poor performance, security, and stability. For more information about how to apply for a public endpoint, see Apply for or release a public endpoint for an ApsaraDB RDS for SQL Server instance.

Check network types

Make sure that the ECS instance and the RDS instance both reside in VPCs or in the classic network.
- View the network type of the ECS instance.
- View the network type of the RDS instance.
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: Migrate the RDS instance from the classic network to the VPC in which the ECS instance to be connected resides. We recommend that you use this method. For more information, see Change 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. This method delivers poor performance, security, and stability. For more information about how to apply for a public endpoint, see Apply for or release a public endpoint for an ApsaraDB RDS for SQL Server instance.
- Methods suitable in scenarios in which the ECS instance resides in the classic network and the RDS instance resides in a VPC:
  - Method 1: Migrate the ECS instance from the classic network to the VPC in which the RDS instance to be connected resides. You can click View Details to the right of the Network Type parameter to view the ID of the VPC in which the RDS instance resides. We recommend that you use this method. For more information, see Migrate an ECS instance.
  - Method 2: Change the network type of the RDS instance from VPC to 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 connect the classic network-type ECS instance to the VPC-type RDS instance over an internal network. For more information, see Enable ClassicLink.
    Note
    If the instances cannot be connected after the ClassicLink feature is enabled, resolve 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. This method delivers poor performance, security, and stability. For more information about how to apply for a public endpoint, see Apply for or release a public endpoint for an ApsaraDB RDS for SQL Server instance.
If the ECS instance and the RDS instance both reside in VPCs, make sure that the instances reside in the same VPC.
- View the ID of the VPC in which the ECS instance resides.
- View the network type of the RDS instance.
If the ECS instance and the RDS instance reside in different VPCs, use one of the following methods to resolve the issue:
- Method 1: Migrate the RDS instance to the VPC in which the ECS instance resides. We recommend that you use this method. For more information, see Change the VPC and vSwitch.
- Method 2: Create a Cloud Enterprise Network (CEN) instance to establish a connection between the two VPCs. For more information about CEN, see Use CEN to enable intra-region network communication.
- Method 3: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. This method delivers poor performance, security, and stability. For more information about how to apply for a public endpoint, see Apply for or release a public endpoint for an ApsaraDB RDS for SQL Server instance.
If the ECS instance and the RDS instance reside in the same VPC and 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 for the connection. You can view the public endpoint of the RDS instance on the Database Connection page in the ApsaraDB RDS console.

Make sure that the public IP address of the on-premises device that you want to connect to the RDS instance is added to an IP address whitelist 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 whitelist of the RDS instance, the device IP address that you added to the IP address whitelist is incorrect. In this case, obtain the correct public IP address of an on-premises device and then add the public IP address to an IP address whitelist of the RDS instance. For more information about how to configure an IP address whitelist, see Configure an IP address whitelist for an ApsaraDB RDS for SQL Server instance.

Note

A public IP address may change. If the public IP address is changed, you cannot use the original public IP address to establish a connection. To maintain a stable connection, we recommend that you use the internal endpoint of the RDS instance and add the internal IP address to the IP address whitelist of the RDS instance.

For more information, see the following topics:

How do I obtain the public IP address of an external server or a client that is connected to an ApsaraDB RDS for SQL Server instance?

Errors reported during the connection between the ECS instance and RDS instance that are created within different Alibaba Cloud accounts

You can use one of the following methods to connect the instances:

Method 1: Use a VPC peering connection. For more information, see VPC Peering Connection. We recommend that you use this method.
Method 2: Use a RAM role and RAM policy. For more information, see RAM roles.
Method 3: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. This method delivers poor performance, security, and stability. For more information about how to apply for a public endpoint, see Apply for or release a public endpoint for an ApsaraDB RDS for SQL Server instance.

Reference

Troubleshoot issues due to which an ApsaraDB RDS instance cannot be connected

Application scope

ApsaraDB RDS