Interesting, I have not seen these errors before either.
Did you remember to drop and recreate the database (to remove unnecessary tables and columns), and run the sql-upgrade task as part of your upgrade process? add your database name in place of "new_database" in the following:
I would also suggest that you restart all services (especially PHP-FPM and memcached), clear the application cache, and try to repopulate the search index after doing the above.
Regarding using CentOS - unfortunately, we do not test installations on CentOS or RHEL, or other Linux flavors than Ubuntu - there are so many possible distributions, each with different packages available, that we cannot possibly cover them all. In many cases for previous CentOS users encountering issues and posting in the forum, it has been a matter of a missing dependency (such as one of the required PHP extensions), or a different version of a dependency that is not currently compatible with AtoM.
I would also recommend that you double-check that ALL required dependencies are available and installed. You might find it useful to look through some of the posts in our forum tagged as "CentOS":
For example, another user has previously shared some instructions on how they got AtoM working on CentOS/RHEL 7.1, here:
We have not tested these instructions ourselves, but hopefully they will give you some ideas. You might also want to try doing a keyword search for "CentOS" since not all older posts have been tagged:
You can read more about how to use the tags in our User forum here:
Good luck! Sorry I don't have more concrete suggestions for these errors - as I said, our ability to support users who install using different Linux distributions is limited. Hopefully the user-created CentOS guide, and/or some of the other CentOS posts will give you some ideas.