When running all test classes from the Setup menu in a Sandbox org at the same time, I am receiving the error "System.DmlException: Insert failed. First exception on row 0; first error: UNABLE_TO_LOCK_ROW, unable to obtain exclusive access to this record:" on occasion which causes the test class to fail.

If I rerun one of these failed tests by itself, the error does not occur. However, I am concerned with what will happen when I go to move these tests to the Production org. Will this locking issue be an issue there as well? Or should I be making a code update to prevent this from happening?


1 Answer 1


Try checking Disable Apex Parallel Testing under Setup/Develop/Apex Test Execution/Options.

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I've encountered this before, and Daniel Ballinger's excellent post here has helped me out.

As Daniel acknowledges in this post, this is a more immediate fix. Ideally, you would be recreating a "clean room" testing scenario with each test, and recreating the database. This exception is being thrown because two tests are attempting to operate on the same record at once.

  • 2
    Sometimes, it's also just a lock on the object itself. For example, trying to upsert custom settings that have the same name in each test may also cause this error, even if SeeAllData=false. The more heavily you rely on custom settings, the more likely it is that you'll need to disable parallel testing to get around this error.
    – sfdcfox
    Dec 9, 2015 at 19:43

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