Gradle task failure

[Lucas9595]

I am using Gradle 4.1, Android plugin 3.0.1, have little experience with Android Studio, and keep getting gradle related problems. The message log is below. What do I change/remove/update in order to get this working?

...

Information:Gradle tasks [:app:generateDebugSources, :app:generateDebugAndroidTestSources, :app:mockableAndroidJar]
/Users/lucascessford/StudioProjects/CSipSimple/app/src/main/res/values/styles.xml
Error:(34, 5) error: invalid resource type 'attr' for parent of style.
Error:(25, 5) error: invalid resource type 'attr' for parent of style.
/Users/lucascessford/StudioProjects/CSipSimple/app/build/intermediates/incremental/mergeDebugResources/merged.dir/values/values.xml
Error:(1490) invalid resource type 'attr' for parent of style.
Error:(1494) invalid resource type 'attr' for parent of style.
Error:java.util.concurrent.ExecutionException: com.android.tools.aapt2.Aapt2Exception: AAPT2 error: check logs for details
Error:Execution failed for task ':app:mergeDebugResources'.

Error: java.util.concurrent.ExecutionException: com.android.tools.aapt2.Aapt2Exception: AAPT2 error: check logs for details
Information:BUILD FAILED in 3s
Information:6 errors
Information:0 warnings
Information:See complete output in console

[tqcenglish]

Try the branch https://github.com/tqcenglish/CSipSimple/tree/remove-ActionBarSherlock

[Lucas9595]

Thank you, a combination of this branch and deleting 'android build version 25' from build.gradle file has resolved the first issues in the error message. The error regarding the 'attr' still remains though. It doesn't recognise attr in the resource xml. What do I need to do to resolve this? do I change it to something, do I remove the 'attr'
This is an example of one of the lines that AS has an issue with

parent="@android:attr/textAppearanceMedium">
invalid resource type 'attr' for parent of style

[grahasmsoni]

use parent="@android:style/TextAppearance.Medium">
also disable AAPT2
also remove appcompatv7 and include actionbarsherlock in your dependencies