Region [TMS_BLOCK_v2] Problem loading keys for file TMS_BLOCK_v2

[naoliv]

I am unsure if it's related with #14017 but while starting JOSM I saw this:

[INFO] BlockDiskCache - Region [TMS_BLOCK_v2] Constructing BlockDiskCache with attributes 
BlockDiskAttributes 
 DiskPath [/home/naoliv/.josm/cache/tiles]
 MaxKeySize [524288]
 MaxPurgatorySize [5000]
 BlockSizeBytes [4096]
 KeyPersistenceIntervalSeconds [300]
 DiskLimitType [SIZE]
[INFO] BlockDiskCache - Region [TMS_BLOCK_v2] Cache file root directory: [/home/naoliv/.josm/cache/tiles]
[INFO] BlockDisk - Constructing BlockDisk, blockSizeBytes [4096]
[INFO] BlockDiskKeyStore - Region [TMS_BLOCK_v2] Cache file root directory [/home/naoliv/.josm/cache/tiles]
[INFO] BlockDiskKeyStore - Region [TMS_BLOCK_v2] Key File [/home/naoliv/.josm/cache/tiles/TMS_BLOCK_v2.key]
[INFO] BlockDiskKeyStore - Region [TMS_BLOCK_v2] Loading keys for /home/naoliv/.josm/cache/tiles/TMS_BLOCK_v2.key
[INFO] BlockDiskKeyStore - Region [TMS_BLOCK_v2] Set maxKeySize to: '524288'
[ERROR] BlockDiskKeyStore - Region [TMS_BLOCK_v2] Problem loading keys for file TMS_BLOCK_v2 <java.io.InvalidClassException: org.apache.commons.jcs.auxiliary.disk.block.BlockDiskElementDescriptor; local class incompatible: stream classdesc serialVersionUID = 6647508557145541119, local class serialVersionUID = -1400659301208101411>java.io.InvalidClassException: org.apache.commons.jcs.auxiliary.disk.block.BlockDiskElementDescriptor; local class incompatible: stream classdesc serialVersionUID = 6647508557145541119, local class serialVersionUID = -1400659301208101411
	at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:616)
	at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1630)
	at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1521)
	at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1781)
	at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1353)
	at java.io.ObjectInputStream.readObject(ObjectInputStream.java:373)
	at org.apache.commons.jcs.auxiliary.disk.block.BlockDiskKeyStore.loadKeys(BlockDiskKeyStore.java:274)
	at org.apache.commons.jcs.auxiliary.disk.block.BlockDiskKeyStore.<init>(BlockDiskKeyStore.java:120)
	at org.apache.commons.jcs.auxiliary.disk.block.BlockDiskCache.<init>(BlockDiskCache.java:143)
	at org.apache.commons.jcs.auxiliary.disk.block.BlockDiskCacheFactory.createCache(BlockDiskCacheFactory.java:60)
	at org.apache.commons.jcs.auxiliary.disk.block.BlockDiskCacheFactory.createCache(BlockDiskCacheFactory.java:33)
	at org.openstreetmap.josm.data.cache.JCSCacheManager.getCacheInner(JCSCacheManager.java:179)
	at org.openstreetmap.josm.data.cache.JCSCacheManager.getCache(JCSCacheManager.java:166)
	at org.openstreetmap.josm.gui.layer.AbstractCachedTileSourceLayer.getCache(AbstractCachedTileSourceLayer.java:128)
	at org.openstreetmap.josm.gui.layer.TMSLayer.getCache(TMSLayer.java:147)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

[WARN] BlockDiskCache - Region [TMS_BLOCK_v2] Resetting cache
[INFO] BlockDiskKeyStore - Region [TMS_BLOCK_v2] Saving keys to [/home/naoliv/.josm/cache/tiles/TMS_BLOCK_v2.key], key count [0]
[INFO] BlockDiskKeyStore - Region [TMS_BLOCK_v2] Finished saving keys. It took 3ms. to store 0 keys.  Key file length [4]
[INFO] BlockDiskCache - Region [TMS_BLOCK_v2] Block Disk Cache is alive.

JOSM:

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2016-11-20 17:33:33 +0100 (Sun, 20 Nov 2016)
Build-Date:2016-11-21 02:34:51
Revision:11288
Relative:URL: ^/trunk

Identification: JOSM/1.5 (11288 pt_BR) Linux Debian GNU/Linux unstable (sid)
Memory Usage: 247 MB / 4029 MB (59 MB allocated, but free)
Java version: 1.8.0_111-8u111-b14-3-b14, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Java package: openjdk-8-jre:amd64-8u111-b14-3
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-11
VM arguments: [-Dawt.useSystemAAFontSettings=on]

Plugins:
+ AddrInterpolation (32699)
+ Create_grid_of_ways (32699)
+ FastDraw (32938)
+ FixAddresses (32796)
+ ImportImagePlugin (32699)
+ OpeningHoursEditor (32699)
+ PicLayer (32796)
+ SimplifyArea (32796)
+ apache-commons (32699)
+ buildings_tools (32944)
+ download_along (32946)
+ editgpx (32699)
+ ejml (32680)
+ geojson (1479298892)
+ geotools (33042)
+ graphview (32796)
+ jogl (1.0.46)
+ jts (32699)
+ kendzi3d (1.0.192)
+ kendzi3d-resources (0.0.1)
+ log4j (32699)
+ measurement (32936)
+ merge-overlap (32699)
+ opendata (33051)
+ pdfimport (32796)
+ photo_geotagging (32699)
+ poly (32699)
+ reverter (32796)
+ tageditor (33021)
+ tagging-preset-tester (32869)
+ todo (30000)
+ turnlanes-tagging (252)
+ turnrestrictions (32796)
+ undelete (32699)
+ utilsplugin2 (32815)

[wiktorn]

It looks more like #11724 we discussed some time ago. I don't have any clue, why it might occur on your system.