Centos 7 zabbix server and centos 6.7 DataBase

Perhaps your database is broken or has the wrong structure.

• all tables must have InnoDB engine;
• PK column in the parent table (items.itemid) and FK column (application_prototype.itemid) must be same data type;
  ...

Dear Alexander, all tables have InnoDB engine.
How can I validate than
PK column in the parent table (items.itemid) and FK column (application_prototype.itemid) are the same data type ?

You can check it by command show create table <table_name>;. Field itemid must be `itemid` bigint(20) unsigned NOT NULL in both tables.

Please attach a DB schema dump before an upgrade (mysqldump -d <database_name> | gzip -c > schema.dump.gz).

I had a similar issue except I am using postgres 9.4 on Debian Jessie. I was able to fix it myself though:

2016-02-25T08:57:28.582753-05:00 zabbix zabbix_server[1548]: [Z3005] query failed: [0] PGRES_FATAL_ERROR:ERROR:  there is no unique constraint matching given keys for referenced table "applications"#012 [alter table application_discovery add constraint c_application_discovery_1 foreign key (applicationid) references applications (applicationid) on delete cascade]
2016-02-25T08:57:28.582839-05:00 zabbix zabbix_server[1548]: database upgrade failed

I was able to fix it by adding the necessary constraint to the applications table:

zabbix=# ALTER TABLE applications ADD CONSTRAINT constraint_name UNIQUE (applicationid);

After I started the zabbix server again, the upgrade finished and the server started fine.

Dear Alexander, I check the tables and attach a DB schema dump before an upgrade:

application_prototype | CREATE TABLE `application_prototype` (
  `application_prototypeid` bigint(20) unsigned NOT NULL,

items | CREATE TABLE `items` (
  `itemid` bigint(20) unsigned NOT NULL,

Now, display other error

[Z3005] query failed: [1050] Table 'application_prototype' already exists [create table application_prototype (
application_prototypeid bigint unsigned not null,
itemid bigint unsigned not null,
templateid bigint unsigned,
name varchar(255) default '' not null,
primary key (application_prototypeid)
) engine=innodb]
 23984:20160225:220228.783 database upgrade failed

I can recall the Can't create table 'zabbix.#sql-RANDOM-CHARACTERS-HERE' error message every time when new major versions is released.
And it never was confirmed that thee is a problem in zabbix, for example ZBX-4729, ZBX-7640, ZBX-9111 and there are linked and also other.

I feel that it can happen for MySQL itself randomly, but it's not a problem of zabbix.

Tyler, you have added constrain not according to zabbix schema, so don't be surprised that you will get some issues in future.

Cristhian, your latest data shows that you did something wrong manually (looks like created table application_prototype manually).
We should not consider mistakes introduced by users. You can ask help here http://zabbix.org/wiki/Getting_help

I think this issue also will be closed as won't fix.

Dear Oleksiy to perform the upgrade I returned to restore the database that I had; taking into account the recommendation of Alexander, the error message display in the logs after performing the upgrade I have not created any table or made any changes manually.

Cristhian, Restoring from a mysql dump of previous version do not delete newly created tables, but it restores db patch level value.
Correct way is to recreating database before restoration from backup ! (I don't want to play in games by suggesting to drop different tables)

Thanks for closing it, but would be also nice to get a feedback how the initial problem was resolved.

Dear Oleksiy.

To solve the first problem, I DROP zabbix DB and create the database again as if it were an initial installation, reviewing and taking into account the recommendations of Alexander Vladishev, after this restore DB; the second problem I resolved by DROP the tables that had error in my case were "application_prototype", "application_discovery" and "opinventory" after that the upgrade of zabbix DB was completed. I don't now the repercuriones will this future but it was the only way I found to resolve it.

...you should not have dropped any tables after the upgrade. but we're in the support area again, so please see http://zabbix.org/wiki/Getting_help