diff --git a/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/bulk_actions.tsx b/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/bulk_actions.tsx
index c859d585f4d82..de27d5fada755 100644
--- a/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/bulk_actions.tsx
+++ b/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/components/bulk_actions.tsx
@@ -148,12 +148,21 @@ export const AgentBulkActions: React.FunctionComponent<{
     },
   ];
 
+  const showSelectEverything =
+    selectionMode === 'manual' &&
+    selectedAgents.length === selectableAgents &&
+    selectableAgents < totalAgents;
+
+  const totalActiveAgents = totalAgents - totalInactiveAgents;
+  const agentCount = selectionMode === 'manual' ? selectedAgents.length : totalActiveAgents;
+  const agents = selectionMode === 'manual' ? selectedAgents : currentQuery;
+
   return (
     <>
       {isReassignFlyoutOpen && (
         <EuiPortal>
           <AgentReassignAgentPolicyFlyout
-            agents={selectionMode === 'manual' ? selectedAgents : currentQuery}
+            agents={agents}
             onClose={() => {
               setIsReassignFlyoutOpen(false);
               refreshAgents();
@@ -164,10 +173,8 @@ export const AgentBulkActions: React.FunctionComponent<{
       {isUnenrollModalOpen && (
         <EuiPortal>
           <AgentUnenrollAgentModal
-            agents={selectionMode === 'manual' ? selectedAgents : currentQuery}
-            agentCount={
-              selectionMode === 'manual' ? selectedAgents.length : totalAgents - totalInactiveAgents
-            }
+            agents={agents}
+            agentCount={agentCount}
             onClose={() => {
               setIsUnenrollModalOpen(false);
               refreshAgents();
@@ -179,10 +186,8 @@ export const AgentBulkActions: React.FunctionComponent<{
         <EuiPortal>
           <AgentUpgradeAgentModal
             version={kibanaVersion}
-            agents={selectionMode === 'manual' ? selectedAgents : currentQuery}
-            agentCount={
-              selectionMode === 'manual' ? selectedAgents.length : totalAgents - totalInactiveAgents
-            }
+            agents={agents}
+            agentCount={agentCount}
             onClose={() => {
               setIsUpgradeModalOpen(false);
               refreshAgents();
@@ -230,12 +235,9 @@ export const AgentBulkActions: React.FunctionComponent<{
                   >
                     <FormattedMessage
                       id="xpack.fleet.agentBulkActions.agentsSelected"
-                      defaultMessage="{count, plural, one {# agent} other {# agents}} selected"
+                      defaultMessage="{count, plural, one {# agent} other {# agents} =all {All agents}} selected"
                       values={{
-                        count:
-                          selectionMode === 'manual'
-                            ? selectedAgents.length
-                            : Math.min(totalAgents - totalInactiveAgents, SO_SEARCH_LIMIT),
+                        count: selectionMode === 'manual' ? selectedAgents.length : 'all',
                       }}
                     />
                   </Button>
@@ -248,9 +250,7 @@ export const AgentBulkActions: React.FunctionComponent<{
                 <EuiContextMenu initialPanelId={0} panels={panels} />
               </EuiPopover>
             </EuiFlexItem>
-            {selectionMode === 'manual' &&
-            selectedAgents.length === selectableAgents &&
-            selectableAgents < totalAgents ? (
+            {showSelectEverything ? (
               <EuiFlexItem grow={false}>
                 <Button
                   size="xs"
diff --git a/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/index.tsx b/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/index.tsx
index faf5da5f17f6b..309209633aab7 100644
--- a/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/index.tsx
+++ b/x-pack/plugins/fleet/public/applications/fleet/sections/agents/agent_list_page/index.tsx
@@ -332,6 +332,14 @@ export const AgentListPage: React.FunctionComponent<{}> = () => {
     }, {} as { [k: string]: AgentPolicy });
   }, [agentPolicies]);
 
+  const isAgentSelectable = (agent: Agent) => {
+    if (!agent.active) return false;
+
+    const agentPolicy = agentPolicies.find((p) => p.id === agent.policy_id);
+    const isManaged = agent.policy_id && agentPolicy?.is_managed === true;
+    return !isManaged;
+  };
+
   const columns = [
     {
       field: 'local_metadata.host.hostname',
@@ -358,7 +366,7 @@ export const AgentListPage: React.FunctionComponent<{}> = () => {
         defaultMessage: 'Agent policy',
       }),
       render: (policyId: string, agent: Agent) => {
-        const policyName = agentPolicies.find((p) => p.id === policyId)?.name;
+        const policyName = agentPoliciesIndexedById[policyId]?.name;
         return (
           <EuiFlexGroup gutterSize="s" alignItems="center" style={{ minWidth: 0 }}>
             <EuiFlexItem grow={false} className="eui-textTruncate">
@@ -549,7 +557,7 @@ export const AgentListPage: React.FunctionComponent<{}> = () => {
         totalAgents={totalAgents}
         totalInactiveAgents={totalInactiveAgents}
         agentStatus={agentsStatus}
-        selectableAgents={agents?.filter((agent) => agent.active).length || 0}
+        selectableAgents={agents?.filter(isAgentSelectable).length || 0}
         selectionMode={selectionMode}
         setSelectionMode={setSelectionMode}
         currentQuery={kuery}
@@ -613,7 +621,17 @@ export const AgentListPage: React.FunctionComponent<{}> = () => {
                   setSelectedAgents(newAgents);
                   setSelectionMode('manual');
                 },
-                selectable: (agent: Agent) => agent.active,
+                selectable: isAgentSelectable,
+                selectableMessage: (selectable, agent) => {
+                  if (selectable) return '';
+                  if (!agent.active) {
+                    return 'This agent is not active';
+                  }
+                  if (agent.policy_id && agentPoliciesIndexedById[agent.policy_id].is_managed) {
+                    return 'This action is not available for agents enrolled in an externally managed agent policy';
+                  }
+                  return '';
+                },
               }
             : undefined
         }
diff --git a/x-pack/plugins/fleet/public/applications/fleet/sections/agents/components/agent_upgrade_modal/index.tsx b/x-pack/plugins/fleet/public/applications/fleet/sections/agents/components/agent_upgrade_modal/index.tsx
index e8a4049d129c1..19ef618c144cc 100644
--- a/x-pack/plugins/fleet/public/applications/fleet/sections/agents/components/agent_upgrade_modal/index.tsx
+++ b/x-pack/plugins/fleet/public/applications/fleet/sections/agents/components/agent_upgrade_modal/index.tsx
@@ -33,10 +33,11 @@ export const AgentUpgradeAgentModal: React.FunctionComponent<Props> = ({
   const { notifications } = useStartServices();
   const [isSubmitting, setIsSubmitting] = useState(false);
   const isSingleAgent = Array.isArray(agents) && agents.length === 1;
+  const isAllAgents = agents === '';
   async function onSubmit() {
     try {
       setIsSubmitting(true);
-      const { error } = isSingleAgent
+      const { data, error } = isSingleAgent
         ? await sendPostAgentUpgrade((agents[0] as Agent).id, {
             version,
           })
@@ -47,22 +48,63 @@ export const AgentUpgradeAgentModal: React.FunctionComponent<Props> = ({
       if (error) {
         throw error;
       }
+
+      const counts = Object.entries(data || {}).reduce(
+        (acc, [agentId, result]) => {
+          ++acc.total;
+          ++acc[result.success ? 'success' : 'error'];
+          return acc;
+        },
+        {
+          total: 0,
+          success: 0,
+          error: 0,
+        }
+      );
       setIsSubmitting(false);
       const successMessage = isSingleAgent
         ? i18n.translate('xpack.fleet.upgradeAgents.successSingleNotificationTitle', {
-            defaultMessage: 'Upgrading agent',
+            defaultMessage: 'Upgraded {count} agent',
+            values: { count: 1 },
           })
         : i18n.translate('xpack.fleet.upgradeAgents.successMultiNotificationTitle', {
-            defaultMessage: 'Upgrading agents',
+            defaultMessage:
+              'Upgraded {isMixed, select, true {{success} of {total}} other {{isAllAgents, select, true {all selected} other {{success}} }}} agents',
+            values: {
+              isMixed: counts.success !== counts.total,
+              success: counts.success,
+              total: counts.total,
+              isAllAgents,
+            },
           });
-      notifications.toasts.addSuccess(successMessage);
+      if (counts.success === counts.total) {
+        notifications.toasts.addSuccess(successMessage);
+      } else if (counts.error === counts.total) {
+        notifications.toasts.addDanger(
+          i18n.translate('xpack.fleet.upgradeAgents.bulkResultAllErrorsNotificationTitle', {
+            defaultMessage:
+              'Error upgrading {count, plural, one {agent} other {{count} agents} =true {all selected agents}}',
+            values: { count: isAllAgents || agentCount },
+          })
+        );
+      } else {
+        notifications.toasts.addWarning({
+          title: successMessage,
+          text: i18n.translate('xpack.fleet.upgradeAgents.bulkResultErrorResultsSummary', {
+            defaultMessage:
+              '{count} {count, plural, one {agent was} other {agents were}} not successful',
+            values: { count: counts.error },
+          }),
+        });
+      }
       onClose();
     } catch (error) {
       setIsSubmitting(false);
       notifications.toasts.addError(error, {
         title: i18n.translate('xpack.fleet.upgradeAgents.fatalErrorNotificationTitle', {
-          defaultMessage: 'Error upgrading {count, plural, one {agent} other {agents}}',
-          values: { count: agentCount },
+          defaultMessage:
+            'Error upgrading {count, plural, one {agent} other {{count} agents} =true {all selected agents}}',
+          values: { count: isAllAgents || agentCount },
         }),
       });
     }
@@ -75,19 +117,20 @@ export const AgentUpgradeAgentModal: React.FunctionComponent<Props> = ({
           <EuiFlexItem grow={false}>
             {isSingleAgent ? (
               <FormattedMessage
-                id="xpack.fleet.upgradeAgents.deleteSingleTitle"
-                defaultMessage="Upgrade agent?"
+                id="xpack.fleet.upgradeAgents.upgradeSingleTitle"
+                defaultMessage="Upgrade agent to latest version"
               />
             ) : (
               <FormattedMessage
-                id="xpack.fleet.upgradeAgents.deleteMultipleTitle"
-                defaultMessage="Upgrade {count} agents?"
-                values={{ count: agentCount }}
+                id="xpack.fleet.upgradeAgents.upgradeMultipleTitle"
+                defaultMessage="Upgrade {count, plural, one {agent} other {{count} agents} =true {all selected agents}} to latest version"
+                values={{ count: isAllAgents || agentCount }}
               />
             )}
           </EuiFlexItem>
           <EuiFlexItem grow={false}>
             <EuiBetaBadge
+              iconType="beaker"
               label={
                 <FormattedMessage
                   id="xpack.fleet.upgradeAgents.experimentalLabel"
@@ -122,8 +165,8 @@ export const AgentUpgradeAgentModal: React.FunctionComponent<Props> = ({
         ) : (
           <FormattedMessage
             id="xpack.fleet.upgradeAgents.confirmMultipleButtonLabel"
-            defaultMessage="Upgrade {count} agents"
-            values={{ count: agentCount }}
+            defaultMessage="Upgrade {count, plural, one {agent} other {{count} agents} =true {all selected agents}}"
+            values={{ count: isAllAgents || agentCount }}
           />
         )
       }
@@ -132,7 +175,7 @@ export const AgentUpgradeAgentModal: React.FunctionComponent<Props> = ({
         {isSingleAgent ? (
           <FormattedMessage
             id="xpack.fleet.upgradeAgents.upgradeSingleDescription"
-            defaultMessage="This action upgrades the agent running on '{hostName}' to version {version}. You can't undo this upgrade."
+            defaultMessage="This action will upgrade the agent running on '{hostName}' to version {version}. This action can not be undone. Are you sure you wish to continue?"
             values={{
               hostName: ((agents[0] as Agent).local_metadata.host as any).hostname,
               version,
@@ -141,7 +184,7 @@ export const AgentUpgradeAgentModal: React.FunctionComponent<Props> = ({
         ) : (
           <FormattedMessage
             id="xpack.fleet.upgradeAgents.upgradeMultipleDescription"
-            defaultMessage="This action upgrades multiple agents to version {version}. You can't undo this upgrade."
+            defaultMessage="This action will upgrade multiple agents to version {version}. This action can not be undone. Are you sure you wish to continue?"
             values={{ version }}
           />
         )}
diff --git a/x-pack/plugins/fleet/server/services/agent_policy.ts b/x-pack/plugins/fleet/server/services/agent_policy.ts
index fa71a67025e3e..be61a70154b11 100644
--- a/x-pack/plugins/fleet/server/services/agent_policy.ts
+++ b/x-pack/plugins/fleet/server/services/agent_policy.ts
@@ -436,7 +436,7 @@ class AgentPolicyService {
     soClient: SavedObjectsClientContract,
     esClient: ElasticsearchClient,
     options?: { user?: AuthenticatedUser }
-  ): Promise<Promise<SavedObjectsBulkUpdateResponse<AgentPolicy>>> {
+  ): Promise<SavedObjectsBulkUpdateResponse<AgentPolicy>> {
     const currentPolicies = await soClient.find<AgentPolicySOAttributes>({
       type: SAVED_OBJECT_TYPE,
       fields: ['revision'],
diff --git a/x-pack/plugins/fleet/server/services/agents/upgrade.ts b/x-pack/plugins/fleet/server/services/agents/upgrade.ts
index 14b8dfaed4d91..d8dd1167d3653 100644
--- a/x-pack/plugins/fleet/server/services/agents/upgrade.ts
+++ b/x-pack/plugins/fleet/server/services/agents/upgrade.ts
@@ -109,8 +109,6 @@ export async function sendUpgradeAgentsActions(
   } else if ('kuery' in options) {
     givenAgents = await getAgents(esClient, options);
   }
-  const givenOrder =
-    'agentIds' in options ? options.agentIds : givenAgents.map((agent) => agent.id);
 
   // get any policy ids from upgradable agents
   const policyIdsToGet = new Set(
@@ -125,25 +123,33 @@ export async function sendUpgradeAgentsActions(
     acc[policy.id] = policy.is_managed;
     return acc;
   }, {});
+  const isManagedAgent = (agent: Agent) => agent.policy_id && managedPolicies[agent.policy_id];
+
+  // results from getAgents with options.kuery '' (or even 'active:false') may include managed agents
+  // filter them out unless options.force
+  const agentsToCheckUpgradeable =
+    'kuery' in options && !options.force
+      ? givenAgents.filter((agent: Agent) => !isManagedAgent(agent))
+      : givenAgents;
 
-  // Filter out agents currently unenrolling, unenrolled, or not upgradeable b/c of version check
   const kibanaVersion = appContextService.getKibanaVersion();
-  const agentResults = await Promise.allSettled(
-    givenAgents.map(async (agent) => {
+  const upgradeableResults = await Promise.allSettled(
+    agentsToCheckUpgradeable.map(async (agent) => {
+      // Filter out agents currently unenrolling, unenrolled, or not upgradeable b/c of version check
       const isAllowed = options.force || isAgentUpgradeable(agent, kibanaVersion);
       if (!isAllowed) {
         throw new IngestManagerError(`${agent.id} is not upgradeable`);
       }
 
-      if (!options.force && agent.policy_id && managedPolicies[agent.policy_id]) {
+      if (!options.force && isManagedAgent(agent)) {
         throw new IngestManagerError(`Cannot upgrade agent in managed policy ${agent.policy_id}`);
       }
       return agent;
     })
   );
 
-  // Filter to agents that do not already use the new agent policy ID
-  const agentsToUpdate = agentResults.reduce<Agent[]>((agents, result, index) => {
+  // Filter & record errors from results
+  const agentsToUpdate = upgradeableResults.reduce<Agent[]>((agents, result, index) => {
     if (result.status === 'fulfilled') {
       agents.push(result.value);
     } else {
@@ -182,6 +188,10 @@ export async function sendUpgradeAgentsActions(
       },
     }))
   );
+
+  const givenOrder =
+    'agentIds' in options ? options.agentIds : agentsToCheckUpgradeable.map((agent) => agent.id);
+
   const orderedOut = givenOrder.map((agentId) => {
     const hasError = agentId in outgoingErrors;
     const result: BulkActionResult = {
diff --git a/x-pack/plugins/translations/translations/ja-JP.json b/x-pack/plugins/translations/translations/ja-JP.json
index 6dc490b4ffc53..42695e458c8e2 100644
--- a/x-pack/plugins/translations/translations/ja-JP.json
+++ b/x-pack/plugins/translations/translations/ja-JP.json
@@ -8730,12 +8730,8 @@
     "xpack.fleet.upgradeAgents.cancelButtonLabel": "キャンセル",
     "xpack.fleet.upgradeAgents.confirmMultipleButtonLabel": "{count}個のエージェントをアップグレード",
     "xpack.fleet.upgradeAgents.confirmSingleButtonLabel": "エージェントをアップグレード",
-    "xpack.fleet.upgradeAgents.deleteMultipleTitle": "{count} 個のエージェントをアップグレードしますか？",
-    "xpack.fleet.upgradeAgents.deleteSingleTitle": "エージェントをアップグレードしますか？",
     "xpack.fleet.upgradeAgents.experimentalLabel": "実験的",
     "xpack.fleet.upgradeAgents.experimentalLabelTooltip": "アップグレードエージェントは今後のリリースで変更または削除される可能性があり、SLA のサポート対象になりません。",
-    "xpack.fleet.upgradeAgents.successMultiNotificationTitle": "エージェントをアップグレード中",
-    "xpack.fleet.upgradeAgents.successSingleNotificationTitle": "エージェントをアップグレード中",
     "xpack.fleet.upgradeAgents.upgradeMultipleDescription": "このアクションにより、複数のエージェントがバージョン{version}にアップグレードされます。このアップグレードは元に戻すことができません。",
     "xpack.fleet.upgradeAgents.upgradeSingleDescription": "このアクションにより、「{hostName}」で実行中のエージェントがバージョン{version}にアップグレードされます。このアップグレードは元に戻すことができません。",
     "xpack.globalSearch.find.invalidLicenseError": "GlobalSearch API は、ライセンス状態が無効であるため、無効になっています。{errorMessage}",
diff --git a/x-pack/plugins/translations/translations/zh-CN.json b/x-pack/plugins/translations/translations/zh-CN.json
index 32574690b13f2..143d89ae3a1d6 100644
--- a/x-pack/plugins/translations/translations/zh-CN.json
+++ b/x-pack/plugins/translations/translations/zh-CN.json
@@ -8818,13 +8818,9 @@
     "xpack.fleet.upgradeAgents.cancelButtonLabel": "取消",
     "xpack.fleet.upgradeAgents.confirmMultipleButtonLabel": "升级 {count} 个代理",
     "xpack.fleet.upgradeAgents.confirmSingleButtonLabel": "升级代理",
-    "xpack.fleet.upgradeAgents.deleteMultipleTitle": "升级 {count} 个代理？",
-    "xpack.fleet.upgradeAgents.deleteSingleTitle": "升级代理？",
     "xpack.fleet.upgradeAgents.experimentalLabel": "实验性",
     "xpack.fleet.upgradeAgents.experimentalLabelTooltip": "在未来的版本中可能会更改或移除升级代理，其不受支持 SLA 的约束。",
     "xpack.fleet.upgradeAgents.fatalErrorNotificationTitle": "升级{count, plural, other {代理}}时出错",
-    "xpack.fleet.upgradeAgents.successMultiNotificationTitle": "正在升级代理",
-    "xpack.fleet.upgradeAgents.successSingleNotificationTitle": "正在升级代理",
     "xpack.fleet.upgradeAgents.upgradeMultipleDescription": "此操作将多个代理升级到版本 {version}。您无法撤消此升级。",
     "xpack.fleet.upgradeAgents.upgradeSingleDescription": "此操作会将运行在“{hostName}”上的代理升级到版本 {version}。您无法撤消此升级。",
     "xpack.globalSearch.find.invalidLicenseError": "GlobalSearch API 已禁用，因为许可状态无效：{errorMessage}",