K9 crashes checking new mail

Hi,
I’m using K9 5.010 on an old Samsung GT i9100 device under Lineage 14 (~ Android 7). Everything was fine until last tuesday when K9 started crashing on checking new mail.

How can I track (and fix) the error?

This is what I found out so far:

IOException: End of stream reached while trying to read line.

K9-Mail version: 5.010
Device make: samsung
Device model: GT-I9100
Android version: 7.1.2

com.fsck.k9.mail.MessagingException: Unable to execute POP3 command
at com.fsck.k9.mail.store.Pop3Store$Pop3Folder.executeSimpleCommand(Pop3Store.java:1162)
at com.fsck.k9.mail.store.Pop3Store$Pop3Folder.executeSimpleCommand(Pop3Store.java:1132)
at com.fsck.k9.mail.store.Pop3Store$Pop3Folder.fetchBody(Pop3Store.java:951)
at com.fsck.k9.mail.store.Pop3Store$Pop3Folder.fetch(Pop3Store.java:817)
at com.fsck.k9.controller.MessagingController.downloadSmallMessages(MessagingController.java:1627)
at com.fsck.k9.controller.MessagingController.downloadMessages(MessagingController.java:1364)
at com.fsck.k9.controller.MessagingController.synchronizeMailboxSynchronous(MessagingController.java:1141)
at com.fsck.k9.controller.MessagingController.access$400(MessagingController.java:111)
at com.fsck.k9.controller.MessagingController$8.run(MessagingController.java:934)
at com.fsck.k9.controller.MessagingController.run(MessagingController.java:435)
at java.lang.Thread.run(Thread.java:761)
Caused by: java.io.IOException: End of stream reached while trying to read line.
at com.fsck.k9.mail.store.Pop3Store$Pop3Folder.readLine(Pop3Store.java:1035)
at com.fsck.k9.mail.store.Pop3Store$Pop3Folder.executeSimpleCommand(Pop3Store.java:1152)
… 10 more

Thanks in advance for helpful hints.