Various embodiments of electrical plug-in connectors are known from the prior art. Electrical plug-in connectors have for example a first and a second contact casing with contacts, the two contact casings being able to be pulled by means of a pivotable stirrup part from a pre-assembly position into an end position. In such case, the stirrup part is rotatably mounted on the first casing, and the second casing has a blocking element which releases pivoting of the stirrup part from the pre-assembly position into the end position only once the two casings are in the pre-assembly position, as described in U.S. Pat. No. 6,540,532 B1.