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?