[Xposed Framework Modules] stormy1777:
Same thing as before on my Marshmellow Android 6.0 (API 23/arm), xposed version 89; cannot install even when removing older apk due to same "App not installd." and "certificate issue" reported above on v6.2.

Obtain the apk:

# cd /sdcard/Download/APK/
# wget https://dl-xda.xposed.info/modules/com.suraj.waext_v29_3cea39.apk
# md5sum *v29*
3cea3990cb0353d4ec93074990835c8e com.suraj.waext_v29_3cea39.apk

Install attempt fails as before:

# date;pm install -r /sdcard/Download/APK/com.suraj.waext_v29_3cea39.apk
Tue Jan 15 11:05:51 GMT 2019
pkg: /sdcard/Download/APK/com.suraj.waext_v29_3cea39.apk
Failure [INSTALL_PARSE_FAILED_NO_CERTIFICATES]

output from 'logcat -d | grep -A30 suraj'

01-15 11:05:53.255 1036 1102 I PackageManager: init_copy idx=0: InstallParams{3d44e42 file=/sdcard/Download/APK/com.suraj.waext_v29_3cea39.apk cid=null}
01-15 11:05:53.255 1036 1102 I PackageManager: Trying to bind to DefaultContainerService
01-15 11:05:53.270 1036 1102 I ActivityManager: Start proc 12938:com.android.defcontainer/u0a5 for service com.android.defcontainer/.DefaultContainerService
01-15 11:05:53.461 1036 1036 I PackageManager: onServiceConnected
01-15 11:05:53.461 1036 1036 I PackageManager: onServiceConnected: true, 0
01-15 11:05:53.462 1036 1102 I PackageManager: mcs_bound
01-15 11:05:53.462 1036 1102 I PackageManager: startCopy UserHandle{-1}: InstallParams{3d44e42 file=/sdcard/Download/APK/com.suraj.waext_v29_3cea39.apk cid=null}
01-15 11:05:53.545 1036 1102 I PackageManager: Apk copy done
01-15 11:05:53.546 1036 1102 I PackageManager: Checking for more work or unbind...
01-15 11:05:53.546 1036 1102 I PackageManager: Posting delayed MCS_UNBIND
01-15 11:05:53.546 1036 1102 I PackageManager: Start parsing apk: null
01-15 11:05:53.554 1036 1102 I PackageManager: Parsing done for apk: null
01-15 11:05:53.576 1036 1102 W PackageManager: Failed collect during installPackageLI
01-15 11:05:53.576 1036 1102 W PackageManager: android.content.pm.PackageParser$PackageParserException: Package /data/app/vmdl882976802.tmp/base.apk has no certificates at entry AndroidManifest.xml
01-15 11:05:53.576 1036 1102 W PackageManager: at android.content.pm.PackageParser.collectCertificates(PackageParser.java:1136)
01-15 11:05:53.576 1036 1102 W PackageManager: at android.content.pm.PackageParser.collectCertificates(PackageParser.java:1087)
01-15 11:05:53.576 1036 1102 W PackageManager: at com.android.server.pm.PackageManagerService.installPackageLI(PackageManagerService.java:12966)
01-15 11:05:53.576 1036 1102 W PackageManager: at com.android.server.pm.PackageManagerService.-wrap25(PackageManagerService.java)
01-15 11:05:53.576 1036 1102 W PackageManager: at com.android.server.pm.PackageManagerService$9.run(PackageManagerService.java:10852)
01-15 11:05:53.576 1036 1102 W PackageManager: at android.os.Handler.handleCallback(Handler.java:815)
01-15 11:05:53.576 1036 1102 W PackageManager: at android.os.Handler.dispatchMessage(Handler.java:104)
01-15 11:05:53.576 1036 1102 W PackageManager: at android.os.Looper.loop(Looper.java:207)
01-15 11:05:53.576 1036 1102 W PackageManager: at android.os.HandlerThread.run(HandlerThread.java:61)
01-15 11:05:53.576 1036 1102 W PackageManager: at com.android.server.ServiceThread.run(ServiceThread.java:46)

Seems like this is the issue?

PackageManager: android.content.pm.PackageParser$PackageParserException: Package /data/app/vmdl882976802.tmp/base.apk has no certificates at entry AndroidManifest.xml

Maybe developer knows why...