### ⚠️ This issue respects the following points: ⚠️
- [X] This is a **bug**, …not a question or a configuration/webserver/proxy issue.
- [X] This issue is **not** already reported on Github _(I've searched it)_.
- [X] Nextcloud Server **is** up to date. See [Maintenance and Release Schedule](https://github.com/nextcloud/server/wiki/Maintenance-and-Release-Schedule) for supported versions.
- [X] Nextcloud Server **is** running on 64bit capable CPU, PHP and OS.
- [X] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).
### Bug description
I updated from nextcloud 25 to 26, and I have 2 instances of nextcloud running on the same server with differnet domains, databases and data folders. The open_basedir and permission structure does not allow them to see/read each other.
Nevertheless, after upgrading I could see errors in nextcloud.log that one instance tries to access files of the oter, and after restarting php-fpm and accessing the second instance, it tried to access files of the other as well - only the first instance I opened kept working, the second showed a HTTP500 and the errors in log with file access.
I have `"memcache.local": "\\OC\\Memcache\\Redis",` enabled with a Redis configuration using a separate `dbindex` for each of the instances.
Only after disabling `apcu` it worked. Even if the memcache config should use Redis with its own database.
### Steps to reproduce
1. Have 2 instances on the same system
2. Upgrade from NC 25 to NC 26
3. Enable apcu
### Expected behavior
Two instances should not interfere with each other, even with apcu they should use an apcuPrefix or similar. I have no idea if this is related to the upgrade or anything else - but that's the only action I executed.
### Installation method
Community Manual installation with Archive
### Nextcloud Server version
26
### Operating system
Debian/Ubuntu
### PHP engine version
PHP 8.1
### Web server
Nginx
### Database engine version
MySQL
### Is this bug present after an update or on a fresh install?
Updated to a major version (ex. 22.2.3 to 23.0.1)
--> Also tested with a FRESH install, same behavior after adding memcached+redis config with active apcu module
### Are you using the Nextcloud Server Encryption module?
None
### What user-backends are you using?
- [X] Default user-backend _(database)_
- [ ] LDAP/ Active Directory
- [ ] SSO - SAML
- [ ] Other
### Configuration report
```shell
{
"system": {
"instanceid": "***REMOVED SENSITIVE VALUE***",
"passwordsalt": "***REMOVED SENSITIVE VALUE***",
"secret": "***REMOVED SENSITIVE VALUE***",
"simpleSignUpLink.shown": false,
"trusted_domains": [
"files.example.com"
],
"datadirectory": "***REMOVED SENSITIVE VALUE***",
"overwrite.cli.url": "https:\/\/files.example.com",
"dbtype": "mysql",
"version": "26.0.0.11",
"dbname": "***REMOVED SENSITIVE VALUE***",
"dbhost": "***REMOVED SENSITIVE VALUE***",
"dbport": "",
"dbtableprefix": "oc_",
"mysql.utf8mb4": true,
"dbuser": "***REMOVED SENSITIVE VALUE***",
"dbpassword": "***REMOVED SENSITIVE VALUE***",
"installed": true,
"mail_from_address": "***REMOVED SENSITIVE VALUE***",
"mail_smtpmode": "smtp",
"mail_smtpauthtype": "LOGIN",
"mail_domain": "***REMOVED SENSITIVE VALUE***",
"maintenance": false,
"theme": "",
"memcache.local": "\\OC\\Memcache\\Redis",
"redis": {
"host": "***REMOVED SENSITIVE VALUE***",
"dbindex": 2,
"port": 6379
},
"updater.release.channel": "stable",
"mail_smtphost": "***REMOVED SENSITIVE VALUE***",
"loglevel": 2,
"default_phone_region": "AT",
"updater.secret": "***REMOVED SENSITIVE VALUE***"
}
}
```
### List of activated Apps
```shell
Enabled:
- activity: 2.18.0
- circles: 26.0.0
- cloud_federation_api: 1.9.0
- comments: 1.16.0
- contactsinteraction: 1.7.0
- dav: 1.25.0
- federatedfilesharing: 1.16.0
- federation: 1.16.0
- files: 1.21.1
- files_pdfviewer: 2.7.0
- files_rightclick: 1.5.0
- files_sharing: 1.18.0
- files_trashbin: 1.16.0
- files_versions: 1.19.1
- firstrunwizard: 2.15.0
- logreader: 2.11.0
- lookup_server_connector: 1.14.0
- nextcloud_announcements: 1.15.0
- notifications: 2.14.0
- oauth2: 1.14.0
- password_policy: 1.16.0
- photos: 2.2.0
- privacy: 1.10.0
- provisioning_api: 1.16.0
- recommendations: 1.5.0
- related_resources: 1.1.0-alpha1
- serverinfo: 1.16.0
- settings: 1.8.0
- sharebymail: 1.16.0
- support: 1.9.0
- survey_client: 1.14.0
- systemtags: 1.16.0
- text: 3.7.2
- theming: 2.1.1
- twofactor_backupcodes: 1.15.0
- updatenotification: 1.16.0
- user_status: 1.6.0
- viewer: 1.10.0
- weather_status: 1.6.0
- workflowengine: 2.8.0
Disabled:
- admin_audit: 1.16.0
- bruteforcesettings: 2.6.0
- dashboard: 7.6.0 (installed 7.0.0)
- encryption: 2.14.0
- files_external: 1.18.0
- suspicious_login: 4.4.0
- twofactor_totp: 8.0.0-alpha.0
- user_ldap: 1.16.0
```
### Nextcloud Signing status
```shell
No errors have been found.
```
### Nextcloud Logs
Tested with a FRESH install. It worked, until I added the memcached config with Redis
```
'memcache.local' => '\\OC\\Memcache\\Redis',
'redis' =>
array (
'host' => 'localhost',
'dbindex' => 2,
'port' => 6379,
),
```
```
{"reqId":"dqf7hKO1FtScvE769qZz","level":3,"time":"2023-04-06T08:20:11+00:00","remoteAddr":"127.0.0.1","user":"webapp2","app":"PHP","method":"GET","url":"/apps/files/?dir=/&fileid=2","message":"include(): open_basedir restriction in effect. File(/var/www/webapp1/apps/firstrunwizard/lib//AppInfo/Application.php) is not within the allowed path(s): /var/www/webapp2/:/usr/lib/php/:/var/lib/php/sessions/:/usr/share/GeoIP/:/tmp/:/opt/nextcloud-data-webapp2) at /var/www/webapp2/lib/composer/composer/ClassLoader.php#578","userAgent":"Mozilla/5.0 (X11; Linux aarch64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36","version":"26.0.0.11","data":{"app":"PHP"}}
```
### Additional info
_No response_