Time machine stuck on preparing for back up

Hello, I have a MacBook Pro 15 2016 and I am trying to get back ups through the time machine which was running fine until the 30th of May. Since then the process freezes at “Preparing for back up”.
I have tried to remove the disk from the TM and then enable it again. I have also formatted the external hard drive but again the same issue.
I have used the same HDD in a MacBook Air and it was running fine.

All my previous back ups are available.

I have stopped and started the back up too many times deleting the .inProgress file.

I have excluded the volume from the antivirus scanning and the spotlight.

I have extracted the logs but I cannot find the issue:

Starting automatic backup

2018-06-04 21:10:38 Backing up to /dev/disk3: /Volumes/Time Machine/Backups.backupdb

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.SnapshotVolumeFSEventStoreUUID' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.SnapshotVolumeLastFSEventID' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.SnapshotVolumeUUID' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.PreviousSnapshotVolumeUUID' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.PreviousSnapshotVolumeName' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.VolumeBytesUsed' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.VolumeIsCaseSensitive' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.fstypename' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Failed to remove attribute 'com.apple.backupd.VolumeIsEncrypted' from 'file:///', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:10:45 Starting age based thinning of Time Machine local snapshots on disk '/'

2018-06-04 21:10:45 Age based thinning deleted Time Machine snapshot 'com.apple.TimeMachine.2018-06-03-134918' on disk '/

2018-06-04 21:10:45 Age based thinning deleted Time Machine snapshot 'com.apple.TimeMachine.2018-06-03-153902' on disk '/

2018-06-04 21:10:45 Age based thinning deleted Time Machine snapshot 'com.apple.TimeMachine.2018-06-03-163757' on disk '/

2018-06-04 21:11:52 Completed thinning of snapshots on disk '/' in 66.7 seconds - current free space: 241,81 GB (241.810.202.624 byte), target free space: 25 GB (25.000.000.000 byte), initial free space: 232,27 GB (232.271.978.496 byte), urgency: 0, remaining snapshots: (

"com.apple.Time "com.apple.TimeMachine.2018-06-04-072337"

2018-06-04 21:11:52 Failed to write unlock record UUIDs as extended attribute for disk '/', error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

2018-06-04 21:11:54 Created Time Machine local snapshot with name 'com.apple.TimeMachine.2018-06-04-211152' on disk '/'

2018-06-04 21:11:56 Declared stable snapshot: com.apple.TimeMachine.2018-06-04-211152

2018-06-04 21:11:56 Mounted stable snapshot: com.apple.TimeMachine.2018-06-04-211152 at path: /Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/MacBook Pro - Panagiotis/2018-06-04-211152/Macintosh HD source: Macintosh HD

2018-06-04 21:11:56 Event store UUIDs don't match for volume: Macintosh HD

2018-06-04 21:11:57 Deep event scan at path:/Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/MacBook Pro - Panagiotis/2018-06-04-211152/Macintosh HD reason:must scan subdirs|new event db|

2018-06-04 21:11:57 Running deep scan - looking for changes after 2018-05-30 17:34:17 +0000

2018-06-04 22:25:24 Finished scan

2018-06-04 22:25:28 Saved event cache at /Volumes/Time Machine/Backups.backupdb/MacBook Pro - Panagiotis/2018-06-04-211156.inProgress/709EAEAC-48FB-4301-A193-53CED9C28E19/.E CCAFEE6-AC86-3EAA-B2F5-BD08E8939254.eventdb

2018-06-04 22:25:28 Not using file event preflight for /

2018-06-04 22:25:29 Snapshot sizing took longer than 4.00 seconds - timing out!

2018-06-04 22:47:48 Will copy (Μηδέν KB) from Macintosh HD

2018-06-04 22:47:50 Unmounted local snapshot: com.apple.TimeMachine.2018-06-04-211152 at path: /Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/MacBook Pro - Panagiotis/2018-06-04-211152/Macintosh HD source: Macintosh HD

2018-06-04 22:47:50 Backup canceled.