Only debuggable packages can be downgraded.
This reflects the change in PackageManager service:
frameworks/base commit 921dd754ab49df0cd580ff96503f7616c4c85f4a.
Bug: 27327503
Change-Id: Ifcc7268cd271640417b8cfc9db81ea954b491cb1
diff --git a/adb/commandline.cpp b/adb/commandline.cpp
index 8e76168..0018226 100644
--- a/adb/commandline.cpp
+++ b/adb/commandline.cpp
@@ -157,7 +157,7 @@
" (-r: replace existing application)\n"
" (-t: allow test packages)\n"
" (-s: install application on sdcard)\n"
- " (-d: allow version code downgrade)\n"
+ " (-d: allow version code downgrade (debuggable packages only))\n"
" (-g: grant all runtime permissions)\n"
" adb install-multiple [-lrtsdpg] <file...>\n"
" - push this package file to the device and install it\n"
@@ -165,7 +165,7 @@
" (-r: replace existing application)\n"
" (-t: allow test packages)\n"
" (-s: install application on sdcard)\n"
- " (-d: allow version code downgrade)\n"
+ " (-d: allow version code downgrade (debuggable packages only))\n"
" (-p: partial application install)\n"
" (-g: grant all runtime permissions)\n"
" adb uninstall [-k] <package> - remove this app package from the device\n"