Hi Mike,
The 16.0 documentation for the LOAD DATABASE command stats that it only formally supports loads from version 12.5.4 and higher. I'm a little bothered that the upgrade message seems to think the dump is from 12.5 rather than 11.9.
It might be best to try first upgrading to 15.7 before going to 16.0. However, lets check the consistency of sysindexes first.
On your 11.9 server, start by running dbcc checktable on the sysindexes table to see if it actually reports a problem there.
use <dbname>
go
dbcc checktable(sysindexes)
go
-bret