Sandbox/IssueExcelExportImport trying to import an xls doesn't work

-- AlessioTurchi - 08 Apr 2019

When I try to import an xls from the sandbox page ("How it works" section) it returns this error:

Foswiki detected an internal error - please check your Foswiki logs and webserver logs for more information.

Can't locate object method "get" via package "AoAdmin" (perhaps you forgot to load "AoAdmin"?)

In the apache logs I find this error

Use of uninitialized value $p2 in concatenation (.) or string at /aogroup/Foswiki-new/lib/Foswiki/Store/PlainFile.pm line 1014.
Use of uninitialized value $p2 in concatenation (.) or string at /aogroup/Foswiki-new/lib/Foswiki/Store/PlainFile.pm line 1014.
Use of uninitialized value $p2 in concatenation (.) or string at /aogroup/Foswiki-new/lib/Foswiki/Store/PlainFile.pm line 1014.
Can't locate object method "get" via package "AoAdmin" (perhaps you forgot to load "AoAdmin"?) at /aogroup/Foswiki-new/lib/Foswiki/Store/PlainFile.pm line 508.
[Mon Apr 08 12:28:58.201612 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of Require all granted: granted
[Mon Apr 08 12:28:58.201646 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of Require not env blockAccess: neutral
[Mon Apr 08 12:28:58.201660 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of <RequireAll>: granted
[Mon Apr 08 12:28:58.201671 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of <RequireAny>: granted
[Mon Apr 08 12:28:58.201766 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of Require all granted: granted
[Mon Apr 08 12:28:58.201785 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of Require not env blockAccess: neutral
[Mon Apr 08 12:28:58.201797 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of <RequireAll>: granted
[Mon Apr 08 12:28:58.201809 2019] [authz_core:debug] [pid 21858:tid 140544692946688] mod_authz_core.c(809): [client 193.206.155.171:50974] AH01626: authorization result of <RequireAny>: granted

Use of uninitialized value $p2 in concatenation (.) or string at /aogroup/Foswiki-new/lib/Foswiki/Store/PlainFile.pm line 1014.

Also when exporting the exported file can't be opened either by office or libreoffice

What is causing this and how can I solve?

Thanks