Hi,
I have made a zip without a top-level folder:
unzip -l customapp.zip
Archive: customapp.zip
Length Date Time Name
--------- ---------- ----- ----
0 2019-01-09 11:25 cd_customapp/
1618 2019-01-09 11:25 cd_customapp/cd_customapp.php
0 2019-01-09 11:25 agent/
1029 2019-01-09 11:25 agent/customapp.vbs
358 2019-01-09 11:25 hook.xml
46 2019-01-09 11:25 README.md
0 2019-01-09 11:25 APACHE/
57 2019-01-09 11:25 APACHE/customapp.conf
321 2019-01-09 11:25 APACHE/Map.pm
18046 2019-01-09 11:25 LICENSE
0 2019-01-09 11:25 language/
0 2019-01-09 11:25 language/fr_FR/
17 2019-01-09 11:25 language/fr_FR/fr_FR.txt
0 2019-01-09 11:25 language/en_GB/
17 2019-01-09 11:25 language/en_GB/en_GB.txt
971 2019-01-09 11:25 install.php
297 2019-01-09 11:25 infos.json
--------- -------
30348 18 files
But OCSinventory reports (debian 10 version 2.5+dfsg1-1) still refuses to install it with
ERROR: customapp is an invalid plugin, check your sources.
Installation aborted !
I looked the OCS code and found

but in the plugins (found here: https://plugins.ocsinventory-ng.org/ then refactorized zip files) have not those plugin_* functions in install.php:

What am I missing? Do I have plugins for a previous version of OCS?
Best regards & thank you all for this excellent piece of software.
L. Zimmerli @SysCo