2.1.0 Error - initializing storage; which file do i have to save to reinstall without data loss

Hi there ,
i had this message with a machine that worked for a long time IMX6 debian 8, snapshot manually installed

2017-12-21 07:10:08.244 [SEVERE] [org.apache.karaf.main.Main] - Could not launch framework
java.lang.RuntimeException: Error initializing storage.
at org.eclipse.osgi.internal.framework.EquinoxContainer.(EquinoxContainer.java:77)
at org.eclipse.osgi.launch.Equinox.(Equinox.java:31)
at org.eclipse.osgi.launch.EquinoxFactory.newFramework(EquinoxFactory.java:24)
at org.apache.karaf.main.Main.launch(Main.java:253)
at org.apache.karaf.main.Main.main(Main.java:177)
Caused by: java.io.UTFDataFormatException: malformed input around byte 57
at java.io.DataInputStream.readUTF(DataInputStream.java:656)
at java.io.DataInputStream.readUTF(DataInputStream.java:564)
at org.eclipse.osgi.container.ModuleDatabase$Persistence.readString(ModuleDatabase.java:1530)
at org.eclipse.osgi.container.ModuleDatabase$Persistence.readModule(ModuleDatabase.java:1097)
at org.eclipse.osgi.container.ModuleDatabase$Persistence.load(ModuleDatabase.java:1015)
at org.eclipse.osgi.container.ModuleDatabase.load(ModuleDatabase.java:879)
at org.eclipse.osgi.storage.Storage.(Storage.java:147)
at org.eclipse.osgi.storage.Storage.createStorage(Storage.java:87)
at org.eclipse.osgi.internal.framework.EquinoxContainer.(EquinoxContainer.java:75)
… 4 more

Reading forum , it seems that i have to reinstall . but i have many config to make again
How can i proceed to save config files