What doctrine provides that not all errors in erroneously admitting evidence requires reversal of conviction?

The doctrine of "harmless error" provides that not all errors in the admission of evidence necessitate a reversal of conviction. Under this doctrine, a conviction may be upheld if the appellate court determines that the error did not affect the outcome of the trial or that the evidence was overwhelmingly sufficient to support the conviction, regardless of the erroneous admission. Essentially, if the court finds that the error was unlikely to have influenced the jury's decision, it may deem the error harmless.