It is a result of the following change in MySQL 5.6.16:
"InnoDB: On Windows, the full-text search (FTS) object ID was not in the expected hexadecimal format. (Bug #16559254)"
That fix adds a new table flag in the InnoDB data dictionary: DICT_TF2_FTS_AUX_HEX_NAME which confuses all pre-5.6.16 servers and XtraBackup, since it is currently based on 5.6.15.
Which would be a purely XtraBackup issue (it is safe to ignore from what I can tell). However, for some reasons the flag is supposed to be used only for FTS tables, however it is actually set for _all_ newly created tables on MySQL 5.6.16+. Which looks like an upstream bug to me. I'm going to report it separately.
It is a result of the following change in MySQL 5.6.16:
"InnoDB: On Windows, the full-text search (FTS) object ID was not in the expected hexadecimal format. (Bug #16559254)"
That fix adds a new table flag in the InnoDB data dictionary: DICT_TF2_ FTS_AUX_ HEX_NAME which confuses all pre-5.6.16 servers and XtraBackup, since it is currently based on 5.6.15.
Which would be a purely XtraBackup issue (it is safe to ignore from what I can tell). However, for some reasons the flag is supposed to be used only for FTS tables, however it is actually set for _all_ newly created tables on MySQL 5.6.16+. Which looks like an upstream bug to me. I'm going to report it separately.