How to debug the error message: "Could not read PGP secret key"?

I’m using gradle signing plugin to publish jars locally, this is my configuration:

    val signingSecretKey = providers.gradleProperty("signing.gnupg.secretKey")
    val signingKeyPassphrase = providers.gradleProperty("signing.gnupg.passphrase")
    signing {
        useGpgCmd()
        if (signingSecretKey.isPresent && signingKeyPassphrase.isPresent) {
            useInMemoryPgpKeys(signingSecretKey.get(), signingKeyPassphrase.get())
            sign(extensions.getByType<PublishingExtension>().publications)
        } else {
            logger.warn("PGP signing key not defined, skipping signing configuration")
        }
    }

The command I used for signing is:

./gradlew sign \
  -Psigning.gnupg.secretKey="YYY" \
  -Psigning.gnupg.passphrase="XXX"

Where XXX is the passphrase when generating the GPG key, and YYY is from gpg --armor --export <KeyID>, it has the following format:

"\n-----BEGIN PGP PRIVATE KEY BLOCK-----   ...   \n-----END PGP PRIVATE KEY BLOCK-----\n"

When I run this command I got the following error:

> Task :core:signMavenPublication FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':core:signMavenPublication'.
> Error while evaluating property 'signatory' of task ':core:signMavenPublication'
   > Could not read PGP secret key

How do I debug this process?

After enabling both stacktrace & --info, the output looks much better, but still doesn’t show much:

> Task :core:signMavenPublication FAILED
Watching 144 directories to track changes
Watching 144 directories to track changes
Watching 144 directories to track changes
Watching 144 directories to track changes
Watching 144 directories to track changes
:core:signMavenPublication (Thread[Execution worker for ':' Thread 8,5,main]) completed. Took 0.001 secs.

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':core:signMavenPublication'.
> Error while evaluating property 'signatory' of task ':core:signMavenPublication'
   > Could not read PGP secret key

* Try:
> Run with --debug option to get more log output.
> Run with --scan to get full insights.

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':core:signMavenPublication'.
        at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:38)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.executeTask(EventFiringTaskExecuter.java:77)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:55)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:52)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:204)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:199)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:157)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:53)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:73)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter.execute(EventFiringTaskExecuter.java:52)
        at org.gradle.execution.plan.LocalTaskNodeExecutor.execute(LocalTaskNodeExecutor.java:74)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:402)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:389)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:382)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:368)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.lambda$run$0(DefaultPlanExecutor.java:127)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.execute(DefaultPlanExecutor.java:191)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.executeNextNode(DefaultPlanExecutor.java:182)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.run(DefaultPlanExecutor.java:124)
        at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
        at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
        at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:61)
Caused by: org.gradle.api.internal.tasks.properties.PropertyEvaluationException: Error while evaluating property 'signatory' of task ':core:signMavenPublication'
        at org.gradle.api.internal.tasks.properties.InputParameterUtils.prepareInputParameterValue(InputParameterUtils.java:33)
        at org.gradle.api.internal.tasks.execution.TaskExecution.lambda$visitRegularInputs$1(TaskExecution.java:312)
        at org.gradle.internal.execution.fingerprint.impl.DefaultInputFingerprinter$InputCollectingVisitor.visitInputProperty(DefaultInputFingerprinter.java:95)
        at org.gradle.api.internal.tasks.execution.TaskExecution.visitRegularInputs(TaskExecution.java:312)
        at org.gradle.internal.execution.fingerprint.impl.DefaultInputFingerprinter.fingerprintInputProperties(DefaultInputFingerprinter.java:54)
        at org.gradle.internal.execution.steps.CaptureStateBeforeExecutionStep.captureExecutionStateWithOutputs(CaptureStateBeforeExecutionStep.java:193)
        at org.gradle.internal.execution.steps.CaptureStateBeforeExecutionStep.lambda$captureExecutionState$1(CaptureStateBeforeExecutionStep.java:141)
        at org.gradle.internal.execution.steps.BuildOperationStep$1.call(BuildOperationStep.java:37)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:204)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:199)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:157)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:53)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:73)
        at org.gradle.internal.execution.steps.BuildOperationStep.operation(BuildOperationStep.java:34)
        at org.gradle.internal.execution.steps.CaptureStateBeforeExecutionStep.captureExecutionState(CaptureStateBeforeExecutionStep.java:130)
        at org.gradle.internal.execution.steps.CaptureStateBeforeExecutionStep.lambda$execute$0(CaptureStateBeforeExecutionStep.java:75)
        at org.gradle.internal.execution.steps.CaptureStateBeforeExecutionStep.execute(CaptureStateBeforeExecutionStep.java:75)
        at org.gradle.internal.execution.steps.CaptureStateBeforeExecutionStep.execute(CaptureStateBeforeExecutionStep.java:50)
        at org.gradle.internal.execution.steps.SkipEmptyWorkStep.lambda$execute$2(SkipEmptyWorkStep.java:93)
        at org.gradle.internal.execution.steps.SkipEmptyWorkStep.execute(SkipEmptyWorkStep.java:93)
        at org.gradle.internal.execution.steps.SkipEmptyWorkStep.execute(SkipEmptyWorkStep.java:34)
        at org.gradle.internal.execution.steps.legacy.MarkSnapshottingInputsStartedStep.execute(MarkSnapshottingInputsStartedStep.java:38)
        at org.gradle.internal.execution.steps.LoadPreviousExecutionStateStep.execute(LoadPreviousExecutionStateStep.java:43)
        at org.gradle.internal.execution.steps.LoadPreviousExecutionStateStep.execute(LoadPreviousExecutionStateStep.java:31)
        at org.gradle.internal.execution.steps.AssignWorkspaceStep.lambda$execute$0(AssignWorkspaceStep.java:40)
        at org.gradle.api.internal.tasks.execution.TaskExecution$3.withWorkspace(TaskExecution.java:284)
        at org.gradle.internal.execution.steps.AssignWorkspaceStep.execute(AssignWorkspaceStep.java:40)
        at org.gradle.internal.execution.steps.AssignWorkspaceStep.execute(AssignWorkspaceStep.java:30)
        at org.gradle.internal.execution.steps.IdentityCacheStep.execute(IdentityCacheStep.java:37)
        at org.gradle.internal.execution.steps.IdentityCacheStep.execute(IdentityCacheStep.java:27)
        at org.gradle.internal.execution.steps.IdentifyStep.execute(IdentifyStep.java:44)
        at org.gradle.internal.execution.steps.IdentifyStep.execute(IdentifyStep.java:33)
        at org.gradle.internal.execution.impl.DefaultExecutionEngine$1.execute(DefaultExecutionEngine.java:76)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeIfValid(ExecuteActionsTaskExecuter.java:142)
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:131)
        at org.gradle.api.internal.tasks.execution.CleanupStaleOutputsExecuter.execute(CleanupStaleOutputsExecuter.java:77)
        at org.gradle.api.internal.tasks.execution.FinalizePropertiesTaskExecuter.execute(FinalizePropertiesTaskExecuter.java:46)
        at org.gradle.api.internal.tasks.execution.ResolveTaskExecutionModeExecuter.execute(ResolveTaskExecutionModeExecuter.java:51)
        at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:57)
        at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:56)
        at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:36)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.executeTask(EventFiringTaskExecuter.java:77)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:55)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:52)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:204)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$CallableBuildOperationWorker.execute(DefaultBuildOperationRunner.java:199)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:66)
        at org.gradle.internal.operations.DefaultBuildOperationRunner$2.execute(DefaultBuildOperationRunner.java:59)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:157)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.execute(DefaultBuildOperationRunner.java:59)
        at org.gradle.internal.operations.DefaultBuildOperationRunner.call(DefaultBuildOperationRunner.java:53)
        at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:73)
        at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter.execute(EventFiringTaskExecuter.java:52)
        at org.gradle.execution.plan.LocalTaskNodeExecutor.execute(LocalTaskNodeExecutor.java:74)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:402)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:389)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:382)
        at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:368)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.lambda$run$0(DefaultPlanExecutor.java:127)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.execute(DefaultPlanExecutor.java:191)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.executeNextNode(DefaultPlanExecutor.java:182)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.run(DefaultPlanExecutor.java:124)
        at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
        at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
        at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:61)
Caused by: org.gradle.api.InvalidUserDataException: Could not read PGP secret key
        at org.gradle.security.internal.pgp.BaseInMemoryPgpSignatoryProvider.createSignatory(BaseInMemoryPgpSignatoryProvider.java:94)
        at org.gradle.security.internal.pgp.BaseInMemoryPgpSignatoryProvider.getDefaultSignatory(BaseInMemoryPgpSignatoryProvider.java:63)
        at org.gradle.security.internal.pgp.BaseInMemoryPgpSignatoryProvider.getDefaultSignatory(BaseInMemoryPgpSignatoryProvider.java:42)
        at org.gradle.plugins.signing.SigningExtension.getSignatory(SigningExtension.java:198)
        at org.gradle.plugins.signing.SigningExtension_Decorated.getSignatory(Unknown Source)
        at org.gradle.plugins.signing.SigningExtension$2.call(SigningExtension.java:291)
        at org.gradle.plugins.signing.SigningExtension$2.call(SigningExtension.java:288)
        at org.gradle.util.internal.GUtil.uncheckedCall(GUtil.java:454)
        at org.gradle.internal.extensibility.ConventionAwareHelper$2.doGetValue(ConventionAwareHelper.java:96)
        at org.gradle.internal.extensibility.ConventionAwareHelper$MappedPropertyImpl.getValue(ConventionAwareHelper.java:147)
        at org.gradle.internal.extensibility.ConventionAwareHelper.getConventionValue(ConventionAwareHelper.java:129)
        at org.gradle.plugins.signing.Sign_Decorated.getSignatory(Unknown Source)
        at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode$BeanPropertyValue$1$1.create(AbstractNestedRuntimeBeanNode.java:77)
        at org.gradle.internal.deprecation.DeprecationLogger.whileDisabled(DeprecationLogger.java:244)
        at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode$BeanPropertyValue$1.get(AbstractNestedRuntimeBeanNode.java:73)
        at com.google.common.base.Suppliers$NonSerializableMemoizingSupplier.get(Suppliers.java:167)
        at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode$BeanPropertyValue.call(AbstractNestedRuntimeBeanNode.java:133)
        at org.gradle.api.internal.tasks.properties.annotations.NestedBeanAnnotationHandler.visitPropertyValue(NestedBeanAnnotationHandler.java:62)
        at org.gradle.api.internal.tasks.properties.bean.AbstractNestedRuntimeBeanNode.visitProperties(AbstractNestedRuntimeBeanNode.java:56)
        at org.gradle.api.internal.tasks.properties.bean.RootRuntimeBeanNode.visitNode(RootRuntimeBeanNode.java:32)
        at org.gradle.api.internal.tasks.properties.DefaultPropertyWalker.visitProperties(DefaultPropertyWalker.java:41)
        at org.gradle.api.internal.tasks.TaskPropertyUtils.visitProperties(TaskPropertyUtils.java:44)
        at org.gradle.api.internal.tasks.properties.DefaultTaskProperties.resolve(DefaultTaskProperties.java:74)
        at org.gradle.execution.plan.LocalTaskNode.resolveMutations(LocalTaskNode.java:200)
        at org.gradle.execution.plan.DefaultExecutionPlan.getResolvedMutationInfo(DefaultExecutionPlan.java:665)
        at org.gradle.execution.plan.DefaultExecutionPlan.selectNext(DefaultExecutionPlan.java:577)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.lambda$executeNextNode$1(DefaultPlanExecutor.java:166)
        at org.gradle.internal.resources.DefaultResourceLockCoordinationService.withStateLock(DefaultResourceLockCoordinationService.java:45)
        at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.executeNextNode(DefaultPlanExecutor.java:155)
        ... 4 more
Caused by: java.io.IOException: secret key ring doesn't start with secret key tag: tag 0xffffffff
        at org.bouncycastle.openpgp.PGPSecretKeyRing.<init>(Unknown Source)
        at org.bouncycastle.openpgp.jcajce.JcaPGPSecretKeyRing.<init>(Unknown Source)
        at org.gradle.security.internal.pgp.BaseInMemoryPgpSignatoryProvider.createSignatory(BaseInMemoryPgpSignatoryProvider.java:80)
        ... 32 more