Troubleshooting SQL Client / Server Connectivity Issues

This section of the Wiki contains troubleshooting techniques for a variety of Microsoft SQL Server client-server connectivity issues. While there are many Knowledge Base articles and forums on the Internet that deal with specific issues, the workflows presented here are more generalized and help you work through unfamiliar issues in a structured manner.

Introduction

When troubleshooting SQL connectivity issues, the thing most often being debugged is your data center. It is very rare that the driver has a connectivity bug and the issue is usually related to an ancillary technology that is used by the driver, such as:

• The DNS service
• The Windows security subsystem (LSSAS) and domain controller
• The file system and registry
• Firewalls, routers, and switches
• Network drivers
• Antivirus and other filter drivers
• Communication bottlenecks between a VM and the host server

Error Messages, Public Articles and Troubleshooters

Before you start a troubleshooting workflow, understand what your error message means and what to do about it. You can also check out public articles and troubleshooters that have already been published.

• 0010 Specific Error Messages and What They Mean
• 0015 Self-Help Articles

Initial Data Collection and Narrowing

This section contains data about the client machine, server machine, and user to gather and have on-hand that will help kick-start any troubleshooting. It also goes over some important questions to narrow the scope of the issue, such as whether it only affects a single machine to being a data-center-wide issue, and some features about your data center, such as whether the issue is local to a single domain or only occurs cross-domain, etc. Knowing these things can rapidly rule out a number of scenarios and narrow the focus of troubleshooting.

• 0100 Initial Data Collection and Scoping Questions

Issue Category

Most issues fall into one of a few types. It is important to determine which category of issue you are experiencing as the workflows can be quite different, for example, a consistent issue vs. an intermittent issue.

• 0200 Consistent Network Issue

• 0300 Intermittent or Periodic Network Issue, including connection timeouts

• 0400 Consistent Authentication Issue

• 0420 Reasons for Consistent Auth Issues

• 0500 Intermittent or Periodic Authentication Issue

• 0600 Credential Delegation (double-hop) Issue

• 0650 SQL Server Linked Server Delegation Issues

• 0660 Other Linked Server Back-end Databases

• 0700 TLS 1.2 Upgrade Workflow

• 0710 SSL Errors after Upgrading to TLS 1.2

• 0720 Advanced SSL Data Capture

• 0750 JDBC and SSL/TLS

• 0770 SQL Server Certificates

• 0755 JDBC Configuring and Troubleshooting

• 0800 Driver Install Checking

• 0810 ODBC Driver Install Checking

• 0820 OLE DB Driver Install Checking

• 0830 .NET Driver Install Checking

• 2000 Specific Issues

Disclaimer

The workflow may not help you resolve your issue completely but should serve to narrow the issue as much as possible and, should you need to contact Microsoft Support, serve to make your support experience more focused and efficient.

A workflow may ask you to use some existing tools on your machine, to download some tools from the Microsoft download site or some other sites, such as those from SysInternals, or to use some scripts or tools from this GitHub site. It may also leverage some Knowledge Base articles that are relevant to your issue.

The workflows are for client-server connection issues using SQL Server drivers and providers to connect to SQL Server. Networking issues related to log shipping, Service Broker, and Always On replication are not covered as they do not use these drivers.

The workflows do not deal with API programming but with driver and infrastructure issues that may cause connectivity issues between your application and Microsoft SQL Server.

Your network may or may not have advanced monitoring systems. These workflows assume that you do not.