There are edge cases where you may escape punishment (Verbotsirrtum) but only if it was unavoidable that you erred. Involuntarily distributing child porn may carry lesser punishment, but it will certainly be investigate unless you can assert a privilege such as common carrier status or inability to control the transmission, as for example Tor nodes could.
This pretty much has never been true, at least in Germany. "Unwissenheit schützt vor Strafe nicht". Even the Roman Law didn't excuse for lack of knowledge https://de.wikipedia.org/wiki/Ignorantia_legis_non_excusat
There are edge cases where you may escape punishment (Verbotsirrtum) but only if it was unavoidable that you erred. Involuntarily distributing child porn may carry lesser punishment, but it will certainly be investigate unless you can assert a privilege such as common carrier status or inability to control the transmission, as for example Tor nodes could.