diff --git a/Changes b/Changes
index bb2a44c3d..8f16347a6 100644
--- a/Changes
+++ b/Changes
@@ -33,6 +33,7 @@ netdiscovery/netinventory:
 * Fix LLDP support
 * Update timeout to backend-collect-timeout configuration when scanning ESX or
   RemoteInventory after a successful scan requested by ToolBox
+* Fix possible concurrency error leading to an unrecoverable blocked task
 
 esx:
 * Fix first connection timeout support
diff --git a/lib/GLPI/Agent/Task/NetDiscovery.pm b/lib/GLPI/Agent/Task/NetDiscovery.pm
index efaa3f13e..d19526d8c 100644
--- a/lib/GLPI/Agent/Task/NetDiscovery.pm
+++ b/lib/GLPI/Agent/Task/NetDiscovery.pm
@@ -300,7 +300,9 @@ sub run {
 
         # Enqueue as ip as possible for each job
         foreach my $jobid (@jobs) {
-            my $job = $jobs{$jobid};
+            # job may has just been done & deleted in run_on_finish() manager callback
+            my $job = $jobs{$jobid}
+                or next;
             next unless $job->ranges;
             next if $job->max_in_queue;
             my $range = $job->range;
diff --git a/lib/GLPI/Agent/Task/NetInventory.pm b/lib/GLPI/Agent/Task/NetInventory.pm
index 9abedf355..5025cd16b 100644
--- a/lib/GLPI/Agent/Task/NetInventory.pm
+++ b/lib/GLPI/Agent/Task/NetInventory.pm
@@ -209,7 +209,9 @@ sub run {
 
         # Enqueue as device as possible for each job
         foreach my $pid (@pids) {
-            my $job = $jobs{$pid};
+            # job may has just been done & deleted in run_on_finish() manager callback
+            my $job = $jobs{$pid}
+                or next;
             next if $job->no_more || $job->max_in_queue;
             my $device = $job->nextdevice
                 or next;