unityで署名付きAPKがビルドできない

###前提・実現したいこと
UnityでAndroid用に署名付きAPKをビルドする

###発生している問題・エラーメッセージ
File->Build Settings->Buildと選択したところ、コンソールに

CommandInvokationFailure: Unable to list target platforms. Please make sure the android sdk path is correct. See the Console for more details. 
C:/Program Files/Java/jdk1.8.0_144\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir="C:\Users\xxxxxxxx\AppData\Local\Android\Sdk\tools" -Dfile.encoding=UTF8 -jar "C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar" -

stderr[
Error:Invalid command android
]
stdout[

]
exit code: 64
UnityEditor.Android.Command.Run (System.Diagnostics.ProcessStartInfo psi, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.AndroidSDKTools.RunCommandInternal (System.String javaExe, System.String sdkToolsDir, System.String[] sdkToolCommand, Int32 memoryMB, System.String workingdir, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.AndroidSDKTools.RunCommandSafe (System.String javaExe, System.String sdkToolsDir, System.String[] sdkToolCommand, Int32 memoryMB, System.String workingdir, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.HostView:OnGUI()

Error building Player: CommandInvokationFailure: Unable to list target platforms. Please make sure the android sdk path is correct. See the Console for more details. 
C:/Program Files/Java/jdk1.8.0_144\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir="C:\Users\xxxxxxxx\AppData\Local\Android\Sdk\tools" -Dfile.encoding=UTF8 -jar "C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar" -

stderr[
Error:Invalid command android
]
stdout[

]
exit code: 64

UnityEditor.BuildPlayerWindow+BuildMethodException: Build failed with errors.
  at UnityEditor.BuildPlayerWindow+DefaultBuildMethods.BuildPlayer (BuildPlayerOptions options) [0x001b9] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:162 
  at UnityEditor.BuildPlayerWindow.CallBuildMethods (Boolean askForBuildLocation, BuildOptions defaultBuildOptions) [0x00050] in C:\buildslave\unity\build\Editor\Mono\BuildPlayerWindowBuildMethods.cs:83 
UnityEditor.HostView:OnGUI()

と出まして、ビルドできません。
###試したこと
http://hackerslab.aktsk.jp/2017/04/26/171821

を参考に、SDKのtoolsフォルダを差し替えてビルドしたところ、コンソールに

CommandInvokationFailure: Failed to sign APK package.
C:\Users\xxxxxxxx\AppData\Local\Android\Sdk\build-tools\26.0.2\apksigner.bat sign --ks "H:/xxxxxxxx/user.keystore" --ks-pass pass:"xxxxxxxx" --ks-key-alias "_" --key-pass pass:"xxxxxxxx" "H:\xxxxxxxx\Temp/StagingArea/Package.apk"

stderr[
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
]
stdout[
-Djava.ext.dirs=C:\Users\xxxxxxxx\AppData\Local\Android\sdk\build-tools\26.0.2\lib is not supported.  Use -classpath instead.
]
exit code: 1
UnityEditor.Android.Command.Run (System.Diagnostics.ProcessStartInfo psi, UnityEditor.Android.WaitingForProcessToExit waitingForProcessToExit, System.String errorMsg)
UnityEditor.Android.PostProcessor.Tasks.TasksCommon.Exec (System.String command, System.String args, System.String workingdir, System.String errorMsg)
UnityEditor.Android.PostProcessor.Tasks.BuildAPK.SignPackage (UnityEditor.Android.PostProcessor.PostProcessorContext context)
UnityEditor.Android.PostProcessor.Tasks.BuildAPK.Execute (UnityEditor.Android.PostProcessor.PostProcessorContext context)
UnityEditor.Android.PostProcessor.PostProcessRunner.RunAllTasks (UnityEditor.Android.PostProcessor.PostProcessorContext context)
UnityEditor.HostView:OnGUI()

と出ました。
以前はこの方法で成功したのですが、今度は失敗しており、何が原因か分かりません。

###補足情報(言語/FW/ツール等のバージョンなど)
Unity 2017.1.1f1 Personal
Android Studio 3.0
キーストアパスワード等はxxxxxxxxで伏せてあります。
SDK,JDKのパスはAndroid Studioのものと合致しており、
Andorid Stuido側では正常に動作しています。

宜しくお願い申し上げます。