<p>ER_XAER_OUTSIDE is thrown when MySQL detects operations executed outside the active XA global transaction context.</p>
<p>MySQL Error 1400: ER_XAER_OUTSIDE arises when a statement runs outside its XA transaction context. Match XA START, END, PREPARE, and COMMIT in the same session to resolve the problem.</p>
XAER_OUTSIDE: Some work is done outside global
MySQL raises error 1400 ER_XAER_OUTSIDE when part of a distributed XA transaction executes outside its declared global context. The server requires that every statement between XA START and XA END belongs exclusively to that XA transaction. If any DML, COMMIT, or ROLLBACK is issued in another session or after the connection leaves XA mode, the check fails and the error appears.
The problem is common in high-concurrency systems that use two-phase commit to coordinate multiple databases or message queues. Leaving the transaction boundaries inconsistent can block further commits and jeopardize data integrity, so immediate correction is essential.
The root cause is that a client issues SQL that changes transactional state while the connection is not inside the XA transaction identified by its xid. MySQL validates the current thread state and fails when it sees an operation linked to no active global transaction.
Typical triggers include mismatched xids, missing XA END statements, connection pool leakage where an unfinished XA branch is reused, or running autocommit DML between XA phases.
Verify that each XA branch follows the strict order XA START 'xid'; perform DML; XA END 'xid'; XA PREPARE 'xid'; XA COMMIT 'xid'; with all commands executed in the same session. Correct any xid typos and avoid intervening autocommit statements.
If an XA branch has leaked, run XA ROLLBACK 'xid'; to clean it, then restart the proper sequence in a fresh connection. Update connection-pool settings so the same physical connection remains pinned to the branch until completion.
Java EE applications using JTA may mismanage pooled connections. Configure your datasource with pinGlobalTxToPhysicalConnection=true so the same connection services the entire XA branch and prevents ER_XAER_OUTSIDE.
Message brokers that hold half-open transactions can time out. Regularly inspect information_schema.innodb_trx for lingering xids and roll them back proactively.
Always close XA transactions promptly. Use try/finally blocks to guarantee XA END and XA PREPARE even when exceptions occur, keeping branches short and predictable.
Starting in MySQL 8.0.17, enable xa_detach_on_close=ON so the server automatically cleans up XA branches when a connection closes unexpectedly.
ER_XAER_NOTA appears when the specified xid is unknown. ER_XAER_INVAL signals invalid arguments to an XA command. ER_XAER_RMFAIL indicates a resource-manager failure during two-phase commit. Diagnose them by inspecting the XA state tables and ensuring the correct command order.
Using different xids in XA END, PREPARE, or COMMIT makes MySQL consider the operation outside the transaction.
Forgetting XA END leaves the branch open, so subsequent commands fail with ER_XAER_OUTSIDE.
Returning a connection to the pool before completing the XA branch lets another thread execute SQL outside the global transaction.
Running autocommit DML between XA START and XA END breaks protocol isolation and triggers the error.
Raised when the xid is unknown to the server, often after a previous rollback.
Signals invalid arguments in an XA command, such as malformed xid or incorrect flags.
Indicates that the resource manager failed, usually due to storage engine issues during two-phase commit.
Shows that the branch has been rolled back and cannot be committed.
No. It blocks the current XA branch but the database keeps running. Realign the command sequence to continue.
The error exists in all XA-capable versions. MySQL 8.0.17 added xa_detach_on_close to simplify cleanup.
No. MySQL enforces XA integrity. Disable XA usage in your application instead.
Galaxy highlights XA boundaries and warns when you mix autocommit DML with XA commands, preventing protocol breaches.
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