Error:ProGuard: [main] java.io.IOException: Can't read proguard_input.jar

When I try to create a build using Android Studio it is showing me these errors
How can I fix it?

Error:ProGuard: [main] java.io.IOException: Can’t read [C:\Users\UNIT.AndroidStudio3.5\system\compile-server\nelson_bac310b6_temp_\proguard_input.jar] (Can’t process class [com/bluebee_consulting/ualla/BuildConfig.class] (Unsupported class version number [52.0] (maximum 51.0, Java 1.7)))
Error:ProGuard: [main] at proguard.InputReader.readInput(InputReader.java:230)
Error:ProGuard: [main] at proguard.InputReader.readInput(InputReader.java:200)
Error:ProGuard: [main] at proguard.InputReader.readInput(InputReader.java:178)
Error:ProGuard: [main] at proguard.InputReader.execute(InputReader.java:78)
Error:ProGuard: [main] at proguard.ProGuard.readInput(ProGuard.java:196)
Error:ProGuard: [main] at proguard.ProGuard.execute(ProGuard.java:78)
Error:ProGuard: [main] at proguard.ProGuard.main(ProGuard.java:492)
Error:ProGuard: [main] Caused by: java.io.IOException: Can’t process class [com/bluebee_consulting/ualla/BuildConfig.class] (Unsupported class version number [52.0] (maximum 51.0, Java 1.7))
Error:ProGuard: [main] at proguard.io.ClassReader.read(ClassReader.java:112)
Error:ProGuard: [main] at proguard.io.FilteredDataEntryReader.read(FilteredDataEntryReader.java:87)
Error:ProGuard: [main] at proguard.io.JarReader.read(JarReader.java:65)
Error:ProGuard: [main] at proguard.io.DirectoryPump.readFiles(DirectoryPump.java:65)
Error:ProGuard: [main] at proguard.io.DirectoryPump.pumpDataEntries(DirectoryPump.java:53)
Error:ProGuard: [main] at proguard.InputReader.readInput(InputReader.java:226)
Error:ProGuard: [main] … 6 more
Error:ProGuard: [main] Caused by: java.lang.UnsupportedOperationException: Unsupported class version number [52.0] (maximum 51.0, Java 1.7)
Error:ProGuard: [main] at proguard.classfile.util.ClassUtil.checkVersionNumbers(ClassUtil.java:140)
Error:ProGuard: [main] at proguard.classfile.io.ProgramClassReader.visitProgramClass(ProgramClassReader.java:88)
Error:ProGuard: [main] at proguard.classfile.ProgramClass.accept(ProgramClass.java:346)
Error:ProGuard: [main] at proguard.io.ClassReader.read(ClassReader.java:91)