Cannot run interpreter.sh permission denied

Our notebooks aren't working and there is the following error in the log file:

{{INFO [2019-08-21 12:33:35,175] ({Exec Default Executor} RemoteInterpreterManagedProcess.java[onProcessFailed]:250) - Interpreter process failed {}}}
{{ {{ org.apache.commons.exec.ExecuteException: Execution failed (Exit value: -559038737. Caused by java.io.IOException: Cannot run program "/home/zep/zeppelin/bin/interpreter.sh" (in directory "."): error=13, Permission denied)}}}}
{{ {{ at org.apache.commons.exec.DefaultExecutor$1.run(DefaultExecutor.java:205)}}}}
{{ {{ at java.lang.Thread.run(Thread.java:748)}}}}
{{ {{ Caused by: java.io.IOException: Cannot run program "/home/zep/zeppelin/bin/interpreter.sh" (in directory "."): error=13, Permission denied}}}}
{{ {{ at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)}}}}
{{ {{ at java.lang.Runtime.exec(Runtime.java:620)}}}}
{{ {{ at org.apache.commons.exec.launcher.Java13CommandLauncher.exec(Java13CommandLauncher.java:61)}}}}
{{ {{ at org.apache.commons.exec.DefaultExecutor.launch(DefaultExecutor.java:279)}}}}
{{ {{ at org.apache.commons.exec.DefaultExecutor.executeInternal(DefaultExecutor.java:336)}}}}
{{ {{ at org.apache.commons.exec.DefaultExecutor.access$200(DefaultExecutor.java:48)}}}}
{{ {{ at org.apache.commons.exec.DefaultExecutor$1.run(DefaultExecutor.java:200)}}}}
{{ {{ ... 1 more}}}}
{{ {{ Caused by: java.io.IOException: error=13, Permission denied}}}}
{{ {{ at java.lang.UNIXProcess.forkAndExec(Native Method)}}}}
{{ {{ at java.lang.UNIXProcess.<init>(UNIXProcess.java:247)}}}}
{{ {{ at java.lang.ProcessImpl.start(ProcessImpl.java:134)}}}}
{{ {{ at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)}}}}
{{ {{ ... 7 more}}}}

 

This is the error message displayed in the notebook and in the logs:

 

WARN [2019-08-21 12:34:35,193] ({pool-2-thread-2} NotebookServer.java[afterStatusChange]:2316) - Job 20190821-121031_890623003 is finished, status: ERROR, exception: java.lang.RuntimeException: , result: %text java.lang.RuntimeException:
{{ at org.apache.zeppelin.interpreter.remote.RemoteInterpreterManagedProcess.start(RemoteInterpreterManagedProcess.java:205)}}
{{ at org.apache.zeppelin.interpreter.ManagedInterpreterGroup.getOrCreateInterpreterProcess(ManagedInterpreterGroup.java:64)}}
{{ at org.apache.zeppelin.interpreter.remote.RemoteInterpreter.getOrCreateInterpreterProcess(RemoteInterpreter.java:111)}}
{{ at org.apache.zeppelin.interpreter.remote.RemoteInterpreter.internal_create(RemoteInterpreter.java:164)}}
{{ at org.apache.zeppelin.interpreter.remote.RemoteInterpreter.open(RemoteInterpreter.java:132)}}
{{ at org.apache.zeppelin.interpreter.remote.RemoteInterpreter.getFormType(RemoteInterpreter.java:299)}}
{{ at org.apache.zeppelin.notebook.Paragraph.jobRun(Paragraph.java:407)}}
{{ at org.apache.zeppelin.scheduler.Job.run(Job.java:188)}}
{{ at org.apache.zeppelin.scheduler.RemoteScheduler$JobRunner.run(RemoteScheduler.java:315)}}
{{ at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)}}
{{ at java.util.concurrent.FutureTask.run(FutureTask.java:266)}}
{{ at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)}}
{{ at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)}}
{{ at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)}}
{{ at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)}}
{

{ at java.lang.Thread.run(Thread.java:748)}

}