How to Fix SQLite Database is Locked Error?

Have you stumbled upon the “SQLite database is locked error code 5”? While performing a query, a user may encounter an Error where the database is locked.

Read the article to know the common causes of why this error occurs and the possible fixes. SQLite is a simple RDBMS(Relational Database Management System) in the C library.  It is not a client-server database engine, unlike other Database Management Systems.

Reasons Behind Sqlite Error Database is Locked Code 5

The error occurs mainly when a user executes two inappropriate transactions in any database against the same connection.

This Error message communicates that an identical process can’t complete due to conflict with the transaction utilizing the same database connection or a separate database connection working on a shared cache.

Some Scenarios for SQLite Database is Locked Error Code 5

Being a lightweight database, SQLite can’t handle a high level of concurrency.

Here are a few such instances:

  1. Using a table to write where the SELECT operation is already active.
  2. You are trying to perform two SELECT operations on the same table at the same time in a multi-thread application.
  3. Using DROP or CREATE on an index or a table, while the SELECT statement is pending. The reason being Sqlite3_() returns the value SQLITE_DONE after the SELECT statement operates. Until Sqlite3_reset() or Sqlite3_finalize() are called the SELECT statement is not complete.
  4. An NFS locking issue may generate the error too.

Ways to Fix SQLite error Database is locked code 5

One of the best ways to resolve this error is to create a database backup having no locks on it and replacing the original with its backup copy.

Method 1: Creating a new Backup with no locks

Note: Here x.Sqlite is the database file.

$Sqlite3 .x.Sqlite

Sqlite> .backup main backup .Sqlite

Sqlite> .exit

Now in the same directory, save the file backup. Here we are replacing the old locked up database file with the new unlocked copy of it. As the new file isn’t locked up, so the SQLite Database is locked code 5 is no longer there.

Method 2: Rewriting the Code

Whenever we attempt to make the database handle concurrency more than the default configuration, we face an error.

In this case, rewriting a more efficient version of the code statement can help solve the error and unlock the database.

Method 3: Increase Default Timeout

If a transaction takes more time to execute, it can prevent other threads from accessing the database, thus creating a deadlock. (A scenario in which each thread is waiting for a resource while holding a resource needed by the other thread)

To resolve this issue, SQLite has a lock time out. If it finds out that a thread has been waiting for a lock for more than the default time of 5 seconds, the process terminates, and we face the dreaded SQLite DB is locked error.

To fix this error, you can increase the timeout value from the timeout database option.

Best Fix to Automatically Resolve the SQLite Error

The manual methods are a bit tricky to follow through and sometimes may fail to fix the issue entirely. A user may also face data loss/corruption if some difficulty occurs.

So we use the alternative automated solution via SQLite Database Recovery Software

Using a Recovery Software has other added advantages too, which help in the long run.

Benefits of using an SQLite Database Recovery Software

  1. Support for the repair of corrupt SQLite2 and SQLite3 databases.
  2. Restore SQLite objects like tables, views, triggers, indices.
  3. It comes with the column Mapping feature to save the recovered data into the MBD Database. 
  4. User-Friendly and interactive interface.
  5. It supports all popular Windows versions.

Summing Up

I see you’ve made it to the end of the article. You can go through these fixes one by one to see which one works out.

After you know why the “SQLite database is locked code 5” error occurs with the causes and fix using the manual method as well as using an SQLite Database Recovery Tool. It’s smarter to go for a recovery tool as you can use it as many times as you want in the future too.