Keystore issues, cleanup Settings

[joerg-ks]

Hello
We use the plugin version 4.1 on BitBucket Server 6.5
It seems there's a setting in the global settings for a keystore (myname and a password) and I want to remove this setting, but if I clean the entry and save it , but it is still present.
In the logfile I see the following errors:

2020-08-25 06:08:17,833 ERROR [threadpool:thread-4] c.a.s.i.c.DefaultTransferableStateManager Error while processing asynchronous task
java.lang.RuntimeException: Unable to build keystore from /sbsm01/apps/bsm/bitbucket/bin/myname
at se.bjurr.prnfb.http.ClientKeyStore.(ClientKeyStore.java:36)
at se.bjurr.prnfb.listener.PrnfbPullRequestEventListener.handleEvent(PrnfbPullRequestEventListener.java:109)
at se.bjurr.prnfb.listener.PrnfbPullRequestEventListener.access$000(PrnfbPullRequestEventListener.java:60)
at se.bjurr.prnfb.listener.PrnfbPullRequestEventListener$2.run(PrnfbPullRequestEventListener.java:178)
at com.atlassian.stash.internal.concurrent.DefaultTransferableStateManager$StateTransferringRunnable.run(DefaultTransferableStateManager.java:166)
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.lang.Thread.run(Thread.java:748)
... 1 frame trimmed
Caused by: java.security.KeyStoreException: not found
at java.security.KeyStore.getInstance(KeyStore.java:851)
at se.bjurr.prnfb.http.ClientKeyStore.getKeyStore(ClientKeyStore.java:51)
at se.bjurr.prnfb.http.ClientKeyStore.(ClientKeyStore.java:27)
... 11 common frames omitted
Caused by: java.security.NoSuchAlgorithmException: KeyStore not available
at sun.security.jca.GetInstance.getInstance(GetInstance.java:159)
at java.security.Security.getImpl(Security.java:695)
at java.security.KeyStore.getInstance(KeyStore.java:848)
... 13 common frames omitted

Is there a chance to reset everything or why can't I delete the setting? I removed the plugin and reinstalled, but everything is still present.