Sorry to hear you’re facing problems 
If you’re urgently looking for support to keep your business running, consider checking out our paid support options.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the following as you can (you can cut and paste this into your topic):
Nextcloud version (eg, 10.0.2): 12.0.4.3
Operating system and version (eg, Ubuntu 16.04): Debian Jessie 8
Apache or nginx version (eg, Apache 2.4.25): Apache 2.4.10
PHP version (eg, 5.6): 7.0.26
Is this the first time you’ve seen this error?:
No
Can you reliably replicate it? (If so, please outline steps):
Yes, every time a user tries to share a file/directory a message pops up (at the top of the page) saying “Unspecified share exception”. It looks like it isn’t being shared, but when you reload the page, you do see the location being shared.
It doesn’t matter if you share it with a user or an email recipient.
The issue you are facing:
sharing a location shows an error, but it is being shared.
The output of your Nextcloud log in Admin > Logging:
nothing at the time of the sharing (level 1)
at debug level only things about ldap directory is being logged
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
$CONFIG = array (
‘passwordsalt’ =>
‘secret’ =>
‘trusted_domains’ =>
array (
),
‘datadirectory’ =>
‘overwrite.cli.url’ =>
‘overwriteprotocol’ => ‘https’,
‘dbtype’ => ‘mysql’,
‘version’ => ‘12.0.4.3’,
‘dbname’ => ‘nextcloud’,
‘dbhost’ => ‘10.’,
‘dbport’ => ‘’,
‘dbtableprefix’ => ‘oc_’,
‘dbuser’ =>
‘dbpassword’ =>
‘logtimezone’ => ‘UTC’,
‘installed’ => true,
‘instanceid’ =>
‘mail_smtpmode’ => ‘smtp’,
‘mail_from_address’ => ‘noc’,
‘mail_domain’ =>
‘mail_smtphost’ => ‘127.0.0.1’,
‘mail_smtpport’ => ‘25’,
‘memcache.local’ => ‘\OC\Memcache\Redis’,
‘memcache.locking’ => ‘\OC\Memcache\Redis’,
‘redis’ =>
array (
‘host’ =>
‘port’ => 6379,
),
‘memcache.distributed’ => ‘\OC\Memcache\Redis’,
‘ldapIgnoreNamingRules’ => false,
‘ldapProviderFactory’ => ‘\OCA\User_LDAP\LDAPProviderFactory’,
‘updater.release.channel’ => ‘production’,
‘maintenance’ => false,
‘theme’ => ‘’,
‘loglevel’ => 2,
‘updater.secret’ =>
‘mail_smtpauthtype’ => ‘LOGIN’,
);
The output of your Apache/nginx/system log in /var/log/____:
ip.ad.dr.ess - - [06/Dec/2017:09:54:59 +0100] “GET /ocs/v1.php/apps/files_sharing/api/v1/sharees?format=json&search=test&perPage=200&itemType=folder HTTP/1.1” 200 1307 “-” “Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko”
ip.ad.dr.ess - - [06/Dec/2017:09:55:00 +0100] “POST /ocs/v2.php/apps/files_sharing/api/v1/shares?format=json HTTP/1.1” 403 890 “-” “Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko”
ip.ad.dr.ess - - [06/Dec/2017:09:55:01 +0100] “GET /ocs/v1.php/apps/files_sharing/api/v1/sharees?format=json&search=test+user&perPage=200&itemType=folder HTTP/1.1” 200 1114 “-” “Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko”
apache error log doesn’t show anything at this point in time.
Remember, this information may be requested if it isn’t supplied; for fastest response please provide as much as you can 
Feel free to use a pastebin service, otherwise log files can be indented with 4 spaces on each line to present them in a friendlier way on the forum.