Unmasking SQL Server Error 3930: Why Your Transaction Is Failing and How to Fix It

You're encountering SQL Server Error Msg 3930, which signals a critical issue: "The current transaction cannot be committed and cannot support operations that write to the log file. Roll back the transaction." This error, appearing after your script has run for approximately two hours, specifically at "Procedure xyz Line 19," indicates that the transaction has entered an uncommittable or "doomed" state. Essentially, an earlier problem within the transaction has rendered it invalid, preventing SQL Server from successfully completing it or even logging further changes.

The fact that rearranging script lines or trying different versions doesn't resolve the error strongly suggests the root cause isn't a simple syntax mistake but a more fundamental issue within the transaction's lifecycle or its interaction with the database environment.

Key Insights: Decoding Error 3930

Symptom, Not the Disease: Msg 3930 is typically a secondary error. It means a prior, often unobserved, error has already occurred, marking the transaction as uncommittable. Your primary task is to find this initial culprit.
Forced Rollback: Once a transaction is in this "doomed" state (internally flagged by SQL Server), it cannot be salvaged. The only course of action for this transaction is a ROLLBACK. Any attempt to COMMIT or perform operations that write to the transaction log will trigger Msg 3930.
Long Transactions, Higher Risk: Your script's two-hour runtime increases its vulnerability. Extended transactions can accumulate locks, encounter timeouts, exhaust resources, or hit data-specific issues that only manifest after significant processing.

Understanding the "Doomed" Transaction State

When SQL Server encounters certain types of errors within an active transaction, it can mark that transaction as uncommittable. This is a protective measure to ensure data integrity. Once doomed, the transaction cannot proceed to a successful commit. Any subsequent operations that attempt to write to the transaction log, including the COMMIT TRANSACTION statement itself, will fail with error 3930. The system essentially tells you, "This transaction is broken beyond repair; you must roll it back."

The state of a transaction can be checked using the XACT_STATE() function. If XACT_STATE() returns -1, it indicates the current request has an active transaction, but it is uncommittable. If it returns 1, there's an active, committable transaction. A return value of 0 means there is no active transaction for the current request.

Common Culprits Behind Error 3930

Several underlying issues can lead to a transaction becoming uncommittable. Identifying which one applies to your situation is key to resolving the error.

Diagram showing SQL Server log space management

Issues with transaction log space or health can contribute to transactional errors.

Preceding Unhandled Errors

This is the most frequent cause. An error occurred earlier in your script *within the same transaction* that you might not have noticed, especially if it wasn't severe enough to halt execution immediately but was fatal to the transaction itself. Examples include:

Constraint violations (e.g., primary key, unique key, foreign key, check constraints)
Arithmetic errors (e.g., division by zero, overflow)
Data type conversion errors
Permissions issues on objects accessed mid-transaction

Deadlocks (Error 1205)

A deadlock occurs when two or more processes are waiting for each other to release resources, creating a stalemate. SQL Server resolves deadlocks by choosing one transaction as a "victim," terminating it, and rolling it back. If your transaction was the victim, it becomes uncommittable, and a subsequent attempt to commit would yield Msg 3930. Given the long runtime, the probability of encountering deadlocks due to resource contention increases.

Transaction Log Issues

While Msg 3930 explicitly mentions not being able to write to the log file, this is often a consequence of the doomed state rather than the primary cause. However, genuine log problems can sometimes be the initial trigger:

Log File Full: If the transaction log runs out of space and cannot grow, write operations will fail.
Log File Corruption: Though rarer, physical issues with the log file can cause widespread problems.
I/O Subsystem Problems: Issues with the disk hosting the transaction log can lead to write failures.

Impact of `SET XACT_ABORT ON`

When SET XACT_ABORT ON is active, most Transact-SQL run-time errors will cause the entire transaction to be terminated and rolled back immediately. If this setting is OFF (the default for SSMS connections), some errors might only roll back the statement causing the error, potentially leaving the transaction in an inconsistent or doomed state if not handled correctly. If an error occurs and XACT_ABORT is OFF, but the error is severe enough to doom the transaction, a later COMMIT will fail with Msg 3930.

Trigger or Nested Procedure Failures

If your transaction executes DML statements (INSERT, UPDATE, DELETE) that fire triggers, or if it calls stored procedures that manage their own (nested) transactions, an unhandled error within a trigger or a nested procedure can doom the outer transaction.

Implicit Transactions

If implicit transactions are enabled (SET IMPLICIT_TRANSACTIONS ON), an operation like an INSERT automatically starts a transaction. If an error occurs during that statement, the implicit transaction might become uncommittable.

Troubleshooting Playbook: Finding the Root Cause

Since Msg 3930 is a symptom, your investigation must focus on uncovering the original error that doomed the transaction. This can be challenging, especially in long-running scripts.

1. Scrutinize the SSMS "Messages" Tab and SQL Server Error Logs

Carefully review all messages in the SQL Server Management Studio "Messages" tab that appeared *before* the Msg 3930 error. The actual culprit error message is often listed there. Also, check the SQL Server Error Logs for any relevant entries around the time your script failed. These logs can provide more context or details about the initial failure.

2. Implement Robust Error Handling with `TRY...CATCH`

This is the most effective way to capture the initial error. Wrap your transactional logic within a TRY...CATCH block. Inside the CATCH block, you can inspect the error details and the transaction state.


BEGIN TRANSACTION;

BEGIN TRY
    -- Your long-running script operations here
    -- Example: operations within Procedure xyz, specifically around Line 19
    
    -- Periodically print status or check XACT_STATE() if suspecting issues
    -- PRINT 'Reached checkpoint X';
    -- IF XACT_STATE() = -1 RAISERROR('Transaction doomed before commit attempt!', 16, 1);

    COMMIT TRANSACTION;
    PRINT 'Transaction committed successfully.';
END TRY
BEGIN CATCH
    PRINT 'An error occurred:';
    PRINT 'Error Number: ' + CAST(ERROR_NUMBER() AS VARCHAR(10));
    PRINT 'Error Severity: ' + CAST(ERROR_SEVERITY() AS VARCHAR(10));
    PRINT 'Error State: ' + CAST(ERROR_STATE() AS VARCHAR(10));
    PRINT 'Error Procedure: ' + ISNULL(ERROR_PROCEDURE(), 'N/A');
    PRINT 'Error Line: ' + CAST(ERROR_LINE() AS VARCHAR(10));
    PRINT 'Error Message: ' + ERROR_MESSAGE();

    IF XACT_STATE() <> 0 -- Check if transaction is active
    BEGIN
        PRINT 'Current transaction state (XACT_STATE()): ' + CAST(XACT_STATE() AS VARCHAR(2));
        IF XACT_STATE() = -1
        BEGIN
            PRINT 'Transaction is uncommittable. Rolling back transaction.';
        END
        ELSE
        BEGIN
            PRINT 'Transaction is committable but an error occurred. Rolling back transaction.';
        END
        ROLLBACK TRANSACTION;
        PRINT 'Transaction rolled back.';
    END
    ELSE
    BEGIN
        PRINT 'No active transaction to roll back.';
    END
    
    -- Optionally, re-throw the error to propagate it
    -- THROW; 
END CATCH;

This structure helps identify the exact error that occurred within the TRY block and ensures the transaction is rolled back if it's in an uncommittable state (XACT_STATE() = -1) or if any other error occurs while it's active.

3. Simplify and Isolate

Since your script runs for two hours and fails at a specific line in a procedure, try to isolate the problematic section:

Break Down the Script: If possible, divide the long transaction into smaller, logical units of work. Run these smaller pieces individually to pinpoint which part causes the initial error.
Focus on "Procedure xyz Line 19": Add detailed logging or PRINT statements immediately before and after Line 19 of your procedure xyz to understand the state and data just before the failure.
Test with Specific Data: The error might be data-dependent. If you can identify the data being processed around the time of failure, try to replicate the issue with a smaller, targeted dataset.

4. Check Transaction Log Health and Space

While often a secondary effect, ensure your transaction log isn't full or experiencing issues:

Use DBCC SQLPERF(LOGSPACE); to check log space usage for your database.
Ensure the log file has adequate free space and is configured to auto-grow if necessary.
Review SQL Server error logs for any messages related to log I/O problems.

The following video discusses how to resolve issues when the transaction log file is full, which can sometimes be a precursor to transactional problems, although Msg 3930 itself is more about the transaction's state than just log space.

Video explaining how to resolve a full transaction log in SQL Server.

5. Monitor for Deadlocks

If you suspect deadlocks (Error 1205) as the preceding error:

Enable deadlock tracing using SQL Server Profiler or Extended Events. These tools can capture deadlock graphs, which show the resources and queries involved.
Examine the SQL Server error log for deadlock messages (Msg 1205).

Likelihood of Different Causes for Msg 3930

The radar chart below visualizes the relative likelihood of common factors leading to the Msg 3930 error. "Preceding Hidden Error" and "Inadequate Error Handling" are often highly influential, as they allow the transaction to reach a doomed state without proper intervention.

This chart suggests that while various factors can contribute, the presence of a hidden preceding error, often coupled with insufficient error handling, is a very strong candidate. The duration of your transaction also plays a significant role by increasing the window of opportunity for such issues to arise.

Mapping the Error: Causes, Symptoms, and Solutions

The mindmap below provides a visual overview of SQL Server Error 3930, connecting its common causes, the primary symptom (the error message itself), effective troubleshooting techniques, and ultimate solutions. Understanding these relationships can help structure your diagnostic approach.

mindmap root["SQL Server Error 3930
(Uncommittable Transaction)"] id1["Causes"] id1a["Preceding Unhandled Error
(Constraint Violation, Type Mismatch, etc.)"] id1b["Deadlock (Error 1205)"] id1c["Transaction Log Problems
(Full, Corrupt, I/O Error)"] id1d["SET XACT_ABORT OFF
with Severe Error"] id1e["Trigger/Nested Procedure Failure"] id1f["Resource Exhaustion
(Long Transactions)"] id2["Primary Symptom"] id2a["Msg 3930: 'The current transaction cannot be committed...'"] id2b["Forced ROLLBACK required"] id3["Troubleshooting Techniques"] id3a["Review SSMS Messages Tab & SQL Error Logs for prior errors"] id3b["Implement TRY...CATCH Blocks
Log ERROR_*() functions, Check XACT_STATE()"] id3c["Simplify Script / Isolate Problematic Code
(Focus on Procedure xyz, Line 19)"] id3d["Monitor for Deadlocks (Profiler, Extended Events)"] id3e["Check Transaction Log (DBCC SQLPERF, Auto-growth)"] id3f["Add PRINT statements / Debugging aids"] id4["Solutions & Prevention"] id4a["Identify and Fix the Root Cause Error"] id4b["Ensure Robust Error Handling
(Always ROLLBACK in CATCH if XACT_STATE() = -1)"] id4c["Consider SET XACT_ABORT ON"] id4d["Break Down Long Transactions into Smaller Units"] id4e["Optimize Queries / Indexing (to reduce deadlocks/duration)"] id4f["Regularly Monitor Log Health & Space"]

This mindmap illustrates that Error 3930 is often the tip of the iceberg. The underlying causes (left branches) lead to the error message (center), which then necessitates specific troubleshooting steps (right branches) to arrive at a sustainable solution.

Resolving the "Doomed" Transaction and Preventing Recurrence

Immediate Action: Ensuring Proper Rollback

Regardless of the root cause, when Msg 3930 occurs, the transaction *must* be rolled back. Your CATCH block should always check XACT_STATE() and issue a ROLLBACK TRANSACTION if it's -1 (uncommittable) or 1 (active but needs to be rolled back due to the error).

Addressing the Identified Root Cause

If a preceding error is found: Modify your script to prevent that specific error (e.g., fix data, adjust logic, handle constraint violations gracefully).
If deadlocks are the issue: Analyze the deadlock graph. You might need to optimize queries, improve indexing, adjust transaction isolation levels, or re-sequence operations. In some cases, implementing retry logic for deadlock errors (1205) within the CATCH block can be a valid strategy.
If transaction log space is the problem: Increase log file size, ensure auto-growth is enabled and functional, or take more frequent log backups (in FULL or BULK_LOGGED recovery models) to allow log truncation.

Best Practices for Prevention

To minimize the chances of encountering Error 3930 in the future:

Always Use TRY...CATCH for Transactions: Encapsulate all transactional code within TRY...CATCH blocks for robust error handling.

Consider SET XACT_ABORT ON: This setting simplifies error handling by ensuring most run-time errors automatically roll back the entire transaction. This can prevent transactions from lingering in a doomed state.


SET XACT_ABORT ON;
BEGIN TRY
    BEGIN TRANSACTION;
    -- Your script operations
    COMMIT TRANSACTION;
END TRY
BEGIN CATCH
    IF @@TRANCOUNT > 0
        ROLLBACK TRANSACTION;
    THROW; -- Re-throw the original error after rollback
END CATCH;
SET XACT_ABORT OFF; -- Reset if needed for subsequent batches with different behavior

Keep Transactions Short and Focused: Long-running transactions lock resources for extended periods, increasing the risk of deadlocks, timeouts, and resource contention. Break down large operations into smaller, manageable transactions where possible.
Regular Monitoring and Logging: Proactively monitor SQL Server error logs, performance counters related to transactions and logs, and implement custom logging within your scripts for critical operations.
Thorough Testing: Test scripts, especially those involving complex transactions or long runtimes, under realistic load conditions in a non-production environment.

Troubleshooting Quick Reference Table

This table summarizes common preceding issues that can lead to Error 3930, their typical indicators, and primary diagnostic actions.

Potential Preceding Issue	Typical Indicators / Clues	Primary Diagnostic Actions
Constraint Violation (Primary Key, Unique, Foreign Key, Check)	Error messages like 2627, 2601, 547, 515 prior to Msg 3930.	Examine data being inserted/updated. Review DDL for constraints. Use `TRY...CATCH` to capture specific constraint error.
Deadlock	Error 1205 (Transaction was deadlocked...) prior to Msg 3930.	Enable deadlock trace flags (1204, 1222). Use SQL Profiler/Extended Events for deadlock graphs. Review queries and indexing.
Arithmetic Error (Divide by zero, overflow)	Error messages like 8134, 8115 prior to Msg 3930.	Inspect calculations, data types. Add checks for divisors being zero or data ranges.
Conversion Error	Error messages like 245, 8114 prior to Msg 3930.	Verify data types in comparisons, assignments, and function calls. Use `TRY_CONVERT` or `TRY_CAST`.
Permissions Issue	Error messages related to object access denial (e.g., Msg 229) prior to Msg 3930.	Verify permissions of the executing user/context on all accessed objects.
Transaction Log Full	Error 9002 (Transaction log for database '...' is full) prior to or triggering Msg 3930.	`DBCC SQLPERF(LOGSPACE)`. Check log file size, auto-growth settings. Perform log backup/shrink if appropriate.
Error in Trigger / Nested Procedure	Original error message from within the trigger or procedure context.	Debug the trigger/procedure code. Implement `TRY...CATCH` within them.