After migrating content from Sitecore 6.5 I see dates staying not in canonical 8+ Sitecore format.
Some samples (raw values) from my current project:
Zat the end
20140329T123823:635316935030258782- no need for so many digits
All dates created in Sitecore 8 (I checked
Updated fields) follow the same
What is the best way to change dates format when content is moved from old Sitecore version to a new one?