Redmine

I cannot uplod Files to issues and into Files module in project. There is no progress bar appearing, juns maximal file size (see attached picture].

This appeared after I upgraded redmine from 3.3 to 3.4.5

My curent configuration is
Environment:
Redmine version 3.4.5.stable
Ruby version 2.3.3-p222 (2016-11-21) [x86_64-linux-gnu]
Rails version 4.2.8
Environment production
Database adapter PostgreSQL
SCM:
Git 2.11.0
Filesystem
Redmine plugins:
a_common_libs 2.4.0
redmine_add_ldap_user_to_group 0.1.0
redmine_apijs 5.3.0
redmine_checklists 3.1.11
redmine_contacts 4.1.2
redmine_dmsf 1.6.2 devel
redmine_impersonate 1.0.0
reminderemails 0.0.1
under_construction 2.0.6

In Production.log, there is no error


Started POST "/uploads.js?attachment_id=1&filename=4E_Manual_kol.pdf&content_type=application%2Fpdf" for 10.0.3.110 at 2018-06-14 12:07:11 +0200
Processing by AttachmentsController#upload as JS
Parameters: {"attachment_id"=>"1", "filename"=>"4E_Manual_kol.pdf", "content_type"=>"application/pdf"}
Current user: honza (id=3)
Saving attachment '/opt/redmine/current/files/2018/06/180614120711_4E_Manual_kol.pdf' (5028978 bytes)
APIJS::AttachmentPatch#update_date: exiftool -FastScan -IgnoreMinorErrors -DateTimeOriginal -S3 /opt/redmine/current/files/2018/06/180614120711_4E_Manual_$
Rendered attachments/upload.js.erb (0.8ms)
Completed 200 OK in 202ms (Views: 6.5ms | ActiveRecord: 36.8ms)


In Issues module > The file is stored as expected but no link is visible.
In Files module > Module says "File is invalid", but it is stored as expected (redmine/files/2018/06/...), no link visible

Do you have any hint, what to check?

Many thanks for any clue.