Can not upload and download files after upgrade to 12.0.5

Hi,

after upgrading my seafile server (binary installation on Debian 11) from 11.0.5 to 12.0.14 some things stopped working:

  1. I can not upload files anymore (via Web or Android Client). Uploads are stuck at 0% and never finish.
  2. I can not download/view files anymore. However, all files can be previewed except PDF files. The Webclient just timeouts on downloading the file, shows a 404 on nginx or resets the connection. When downloading a file, I noticed, that the port 8000 is missing in the download link. Manually added the port does not allow a download.

Unfortunately, I can not find any logs, that hint to some error.
seafile.log:
[2025-08-14 10:50:07] [INFO] seafile-session.c(64): fileserver: web_token_expire_time = 3600
[2025-08-14 10:50:07] [INFO] seafile-session.c(76): fileserver: max_index_processing_threads= 3
[2025-08-14 10:50:07] [INFO] seafile-session.c(89): fileserver: fixed_block_size = 8388608
[2025-08-14 10:50:07] [INFO] seafile-session.c(101): fileserver: max_indexing_threads = 1
[2025-08-14 10:50:07] [INFO] ../common/seaf-utils.c(401): Use database Mysql
[2025-08-14 10:50:07] [INFO] http-server.c(196): fileserver: worker_threads = 10
[2025-08-14 10:50:07] [INFO] http-server.c(207): fileserver: verify_client_blocks = 1
[2025-08-14 10:50:07] [INFO] http-server.c(229): fileserver: cluster_shared_temp_file_mode = 600
[2025-08-14 10:50:07] [INFO] socket file exists, delete it anyway

seahub.log:
[2025-08-14 08:19:01] [WARNING] django.request:241 log_response Not Found: /favicon.ico
[2025-08-14 08:19:08] [WARNING] django.request:241 log_response Not Found: /443
[2025-08-14 08:52:34] [WARNING] django.request:241 log_response Not Found: /media/js/pdf/web/viewer.js.map
[2025-08-14 09:41:19] [WARNING] django.request:241 log_response Not Found: /login

Does someone have an idea on what could be wrong?