croped image not uploading with retrofit 2.0

Process: com.solexp.mandionline, PID: 23055
java.lang.NullPointerException: Attempt to invoke interface method 'int java.lang.CharSequence.length()' on a null object reference
at java.util.regex.Matcher.reset(Matcher.java:177)
at java.util.regex.Matcher.(Matcher.java:90)
at java.util.regex.Pattern.matcher(Pattern.java:297)
at okhttp3.MediaType.parse(MediaType.java:51)
at com.solexp.mandionline.activities.ProfileActivity.uploadFile(ProfileActivity.java:594)
at com.solexp.mandionline.activities.ProfileActivity.access$200(ProfileActivity.java:87)
at com.solexp.mandionline.activities.ProfileActivity$7.onClick(ProfileActivity.java:313)
at com.ontbee.legacyforks.cn.pedant.SweetAlert.SweetAlertDialog.onClick(SweetAlertDialog.java:373)
at android.view.View.performClick(View.java:5197)
at android.view.View$PerformClick.run(View.java:20926)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5951)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)