Although the first Android N preview is already available and many older handsets are waiting in line to get Marshmallow, updating to Android 6.0 can sometimes cause serious problems. While other big names in the industry decided to drop software support for various handsets, Sony takes things seriously and has recently updated the Xperia Z5 and Xperia Z5 Premium in Canada.
Unfortunately, the Xperia Care support forum shows that something went wrong. A topic named "Google Play Store has Stopped" after Z5 Premium Marshmallow Update is very popular, having gathered 9 pages so far. For example, MakeAndroidGreat writes "My Z5 keeps saying this after I updated to Marshmallow.
I've tried everything (including installing APKs of the most recent and compatible Play Store and Play Services) except for the factory reset/pc companion/bridge solution, because that sounds horrible." Many others confirmed this.
At last, it should be taken into consideration that it appears like the problem also surfaced "across multiple Marshmallow devices, not just Xperia devices or the Z5 series." Various workarounds have been suggested by users so far, but Sony still has to release a patch. They only confirmed the withdrawal of the Marshmallow update that seems to cause problems and nothing more for now.