MySQL Error 1071 on ugrading from 9.0 to 9.1

Server
,
1

Hi !
I just tried to upgrade my owncloud fron 9.0 to 9.1. The update failed =(.

Steps to reproduce
1. Download owncloud-9.1.0.zip, checked with SHA256 and OGP
2. Unzip in new owncloud dir
3. Copying my config file and 3rd party apps to new installation
4. Run [i]sudo -apache_user php oc upgrade[i]

Expected behaviour
Complete the upgrade to 9.1

Actual behaviour
Update failed withe this message:

Checking whether the database schema for can be updated (this can take a long time depending on the database size)
oc_calendarobjects
4/10 [===========>----------------] 40%OC\DB\MigrationException: An exception occurred while executing 'ALTER TABLE oc_oc_calendarobjects_trc6y1obe3pjt ADD classification INT DEFAULT 0 COMMENT '0 - public, 1 - private, 2 - confidential', CHANGE id idBIGINT UNSIGNED AUTO_INCREMENT NOT NULL, CHANGEuriuriVARCHAR(255) DEFAULT NULL, CHANGEetagetagVARCHAR(32) DEFAULT NULL, CHANGEsizesizeBIGINT UNSIGNED NOT NULL, CHANGEcomponenttypecomponenttypeVARCHAR(8) DEFAULT NULL, CHANGEfirstoccurencefirstoccurenceBIGINT UNSIGNED DEFAULT NULL, CHANGElastoccurencelastoccurenceBIGINT UNSIGNED DEFAULT NULL, CHANGEuiduid VARCHAR(255) DEFAULT NULL':

SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes
Update failed
Maintenance mode is kept active
Reset log level

Server configuration
Operating system: Debian Jessie
Web server: Apache 2.4.10
Database: MySQL Ver 14.14 Distrib 5.5.50, for debian-linux-gnu (i686) using readline 6.3
PHP version: 2.6.0
ownCloud version (see ownCloud admin page): 9.0.0
Updated from an older ownCloud or fresh install: Updated from 8.2
ownCloud log (data/owncloud.log, see https://central.owncloud.org/t/how-to-find-webserver-or-oc-logfile-enable-php-logfile/808):

{"reqId":"d7WJU95hTtc41aAAJeMv","remoteAddr":"","app":"core","message":"starting upgrade from 9.0.0.19 to 9.1.0.15","level":0,"time":"2016-08-09T10:05:$
{"reqId":"d7WJU95hTtc41aAAJeMv","remoteAddr":"","app":"core","message":"Simulated database structure update failed (exception 'OC\DB\MigrationExcepti$
{"reqId":"d7WJU95hTtc41aAAJeMv","remoteAddr":"","app":"core","message":"Exception: {\"Exception\":\"OC\\DB\\MigrationException\",\"Message\":\"An e$
{"reqId":"d7WJU95hTtc41aAAJeMv","remoteAddr":"","app":"core","message":"XCache opcode cache will not be cleared because \"xcache.admin.enable_auth\" is$
{"reqId":"iosZ2zbD9in1p7ijiU4N","remoteAddr":"","app":"core","message":"Error while running background job (class: OC\BackgroundJob\Legacy\RegularJo$
{"reqId":"4W42HkCg5HpQNafxSmRQ","remoteAddr":"","app":"core","message":"XCache opcode cache will not be cleared because \"xcache.admin.enable_auth\" is$

Special configuration (external storage, external authentication, reverse proxy, server-side-encryption): none

Integrity status for oC9+

Technical information
=====================
The following list covers which files have failed the integrity check. Please read
the previous linked documentation to learn more about the errors and how to fix
them.
Results
=======
- core
	- INVALID_HASH
		- 3rdparty/guzzlehttp/guzzle/src/Client.php
		- 3rdparty/patches.txt
	- EXTRA_FILE
		- config.sample.php
Raw output
==========
Array
(
    [core] => Array
        (
            [INVALID_HASH] => Array
                (
                    [3rdparty/guzzlehttp/guzzle/src/Client.php] => Array
                        (
                            [expected] => 34b6d5b6bf056c25c4986eef62b44dd5a8508affc120234394df55c6b9580312d19498b78398c78b55884b393f51c6997deff5c8bfd6578585c7a1fde8d9d604
                            [current] => def9cb679ae55b41a425a57ecb49bd010d948f47f5436e9c619e20fd1185fd9e9a21cc46d43c214bab69f70df771058b85c27f304bafddd54421e1aba3485fb3
                        )
                    [3rdparty/patches.txt] => Array
                    (
                        [expected] => c9c980044146368b809b774e171a2f08345c75a7c622f3153d3c2881ee06dcd9abbe3e342f3ea36b2e8e85c2f77610286de1576c60d14c3532b6ec2fca1a1e1e
                        [current] => 4e5c76601cd13c1122641fd50e47d81abdd5abe75390ab9d1cbb70e59f5d9f88e1c76dafebee17b62a1bccb0fa70b319b76511a3670cdec6398a6a1204026db2
                    )

            )

        [EXTRA_FILE] => Array
            (
                [config.sample.php] => Array
                    (
                        [expected] => 
                        [current] => ea8a9408749c28474b6156ee7dcfc9f487bf1f54a02904d3da00030c1225adb3a082b0b0b865e7bd67f94d389d666a9c7ab0e6aff1318aec1f2c66c322d3bae4
                    )

            )

    )
)

Thanks for some help.

2

Are you using InnoDB engine?

3

yes, i'm using InnoDB

4

what is the charset of the db?

5

charset of owncloud db is utf8
Thx =)

6

Ref for an existing bugreport: