The 'Lock request time out period exceeded' error is a common issue faced by many SQL Server users, especially when dealing with long-running queries or transactions that are holding locks on tables for extended periods. In this article, we will discuss the causes and possible solutions to this problem.

One of the most common scenarios where you may encounter the 'Lock request time out period exceeded' error is when a query or transaction is taking too long to complete and has locked a table or resource for an extended period. This can occur due to various reasons such as:

* A poorly written query that is taking too long to execute

* A large amount of data being processed, leading to long-running transactions

* Insufficient database resources, such as memory or CPU

To troubleshoot the issue, you can use the sysprocesses system view in SQL Server Management Studio (SSMS) to monitor active connections and processes. Here's how:

1. Open SSMS and connect to your database.

2. In the Object Explorer, expand the 'Database' node and select the 'Views' folder.

3. Right-click on the 'sysprocesses' view and select 'Open View'.

4. In the query window, type or paste the following command: `SELECT * FROM sysprocesses WHERE spid = `. Replace `` with the SPID of the connection you are currently using.

5. Note down the SPID of this query window connection in the lower right hand corner of SSMS.

Next, identify the query or transaction that is causing the lock by running the following command:

1. In a new query window, type or paste the command that is timing out due to a lock: `SELECT * FROM WHERE ` (replace `` and `` with your actual table name and condition).

2. This will give you an idea of what query or transaction is holding the lock.

In some cases, you may not have permission to kill processes on the server, making it difficult to resolve the issue. In such scenarios, restarting the SQL Server service may help resolve the problem. However, if this does not work, there are other solutions you can try:

1. Check for any long-running transactions or queries that are holding locks and cancel them if possible.

2. Identify and resolve any performance issues in your database, such as disk bottlenecks or insufficient memory.

3. Optimize your queries to reduce the amount of data being processed and improve overall query performance.

In conclusion, the 'Lock request time out period exceeded' error is a common issue in SQL Server that can occur due to various reasons. By using the sysprocesses system view and identifying the query or transaction causing the lock, you can troubleshoot and resolve this problem. Additionally, restarting the SQL Server service or optimizing your queries can also help resolve this issue.

Lock request time out period exceeded.