Support intro
Sorry to hear you’re facing problems. 
The community help forum (help.nextcloud.com) is for home and non-enterprise users. Support is provided by other community members on a best effort / “as available” basis. All of those responding are volunteering their time to help you.
If you’re using Nextcloud in a business/critical setting, paid and SLA-based support services can be accessed via portal.nextcloud.com where Nextcloud engineers can help ensure your business keeps running smoothly.
Getting help
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- Official documentation (searchable and regularly updated)
- How to topics and FAQs
- Forum search
(Utilizing these existing resources is typically faster. It also helps reduce the load on our generous volunteers while elevating the signal to noise ratio of the forums otherwise arising from the same queries being posted repeatedly).
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can. 
The Basics
- Nextcloud Server version (e.g., 29.x.x):
30.0.5
- Operating system and version (e.g., Ubuntu 24.04):
24.04
- Web server and version (e.g, Apache 2.4.25):
2.4.58
- Reverse proxy and version _(e.g. nginx 1.27.2)
NPM 2.11.1
- PHP version (e.g, 8.3):
8.3
- Is this the first time you’ve seen this error? (Yes / No):
No
- When did this problem seem to first start?
After updating to [Nextcloud Hub 9] (30.0.5)
- Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
replace me
- Are you using CloudfIare, mod_security, or similar? (Yes / No)
No
Summary of the issue you are facing:
[ After updating to [Nextcloud Hub 9] (30.0.2) i get the follow warming:
There are some errors regarding your setup.
**** Some files have not passed the integrity check. List of invalid files… Rescan… For more details see the documentation 
.***
Mail app Version 4.1.2
Steps to replicate it (hint: details matter!):
Log entries
Nextcloud
Please provide the log entries from your Nextcloud log that are generated during the time of problem (via the Copy raw option from Administration settings->Logging screen or from your nextcloud.log located in your data directory). Feel free to use a pastebin/gist service if necessary.
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
=======
- mail
- EXCEPTION
- OC\IntegrityCheck\Exceptions\InvalidSignatureException
- Certificate is not valid.
Raw output
==========
Array
(
[mail] => Array
(
[EXCEPTION] => Array
(
[class] => OC\IntegrityCheck\Exceptions\InvalidSignatureException
[message] => Certificate is not valid.
)
)
)
There was already such a problem a month ago Mail-app failed the integrity check after updating .
Check the signature in the mail 4.1.2 application