diff --git a/modules/indexer/issues/indexer.go b/modules/indexer/issues/indexer.go
index 4db5091762..8530210628 100644
--- a/modules/indexer/issues/indexer.go
+++ b/modules/indexer/issues/indexer.go
@@ -110,7 +110,7 @@ func InitIssueIndexer(syncReindex bool) {
 				return
 			}
 
-			iData := make([]*IndexerData, 0, setting.Indexer.IssueQueueBatchNumber)
+			iData := make([]*IndexerData, 0, len(data))
 			for _, datum := range data {
 				indexerData, ok := datum.(*IndexerData)
 				if !ok {
diff --git a/modules/indexer/issues/indexer_test.go b/modules/indexer/issues/indexer_test.go
index 866e3cc7c9..ba35e37fd8 100644
--- a/modules/indexer/issues/indexer_test.go
+++ b/modules/indexer/issues/indexer_test.go
@@ -34,12 +34,12 @@ func TestBleveSearchIssues(t *testing.T) {
 		assert.Fail(t, "Unable to create temporary directory: %v", err)
 		return
 	}
-	oldQueueDir := setting.Indexer.IssueQueueDir
+
+	setting.Cfg.Section("queue.issue_indexer").Key("DATADIR").MustString(path.Join(tmpIndexerDir, "issues.queue"))
+
 	oldIssuePath := setting.Indexer.IssuePath
-	setting.Indexer.IssueQueueDir = path.Join(tmpIndexerDir, "issues.queue")
 	setting.Indexer.IssuePath = path.Join(tmpIndexerDir, "issues.queue")
 	defer func() {
-		setting.Indexer.IssueQueueDir = oldQueueDir
 		setting.Indexer.IssuePath = oldIssuePath
 		util.RemoveAll(tmpIndexerDir)
 	}()
diff --git a/modules/setting/indexer.go b/modules/setting/indexer.go
index 2e9d8b2883..f103a7464b 100644
--- a/modules/setting/indexer.go
+++ b/modules/setting/indexer.go
@@ -14,32 +14,20 @@ import (
 	"github.com/gobwas/glob"
 )
 
-// enumerates all the indexer queue types
-const (
-	LevelQueueType   = "levelqueue"
-	ChannelQueueType = "channel"
-	RedisQueueType   = "redis"
-)
-
 var (
 	// Indexer settings
 	Indexer = struct {
-		IssueType             string
-		IssuePath             string
-		IssueConnStr          string
-		IssueIndexerName      string
-		IssueQueueType        string // DEPRECATED - replaced by queue.issue_indexer
-		IssueQueueDir         string // DEPRECATED - replaced by queue.issue_indexer
-		IssueQueueConnStr     string // DEPRECATED - replaced by queue.issue_indexer
-		IssueQueueBatchNumber int    // DEPRECATED - replaced by queue.issue_indexer
-		StartupTimeout        time.Duration
+		IssueType        string
+		IssuePath        string
+		IssueConnStr     string
+		IssueIndexerName string
+		StartupTimeout   time.Duration
 
 		RepoIndexerEnabled bool
 		RepoType           string
 		RepoPath           string
 		RepoConnStr        string
 		RepoIndexerName    string
-		UpdateQueueLength  int // DEPRECATED - replaced by queue.issue_indexer
 		MaxIndexerFileSize int64
 		IncludePatterns    []glob.Glob
 		ExcludePatterns    []glob.Glob
@@ -49,7 +37,6 @@ var (
 		IssuePath:        "indexers/issues.bleve",
 		IssueConnStr:     "",
 		IssueIndexerName: "gitea_issues",
-		IssueQueueType:   LevelQueueType,
 
 		RepoIndexerEnabled: false,
 		RepoType:           "bleve",
@@ -72,11 +59,12 @@ func newIndexerService() {
 	Indexer.IssueIndexerName = sec.Key("ISSUE_INDEXER_NAME").MustString(Indexer.IssueIndexerName)
 
 	// The following settings are deprecated and can be overridden by settings in [queue] or [queue.issue_indexer]
-	Indexer.IssueQueueType = sec.Key("ISSUE_INDEXER_QUEUE_TYPE").MustString("")
-	Indexer.IssueQueueDir = filepath.ToSlash(sec.Key("ISSUE_INDEXER_QUEUE_DIR").MustString(""))
-	Indexer.IssueQueueConnStr = sec.Key("ISSUE_INDEXER_QUEUE_CONN_STR").MustString("")
-	Indexer.IssueQueueBatchNumber = sec.Key("ISSUE_INDEXER_QUEUE_BATCH_NUMBER").MustInt(0)
-	Indexer.UpdateQueueLength = sec.Key("UPDATE_BUFFER_LEN").MustInt(0)
+	// FIXME: DEPRECATED to be removed in v1.18.0
+	deprecatedSetting("indexer", "ISSUE_INDEXER_QUEUE_TYPE", "queue.issue_indexer", "TYPE")
+	deprecatedSetting("indexer", "ISSUE_INDEXER_QUEUE_DIR", "queue.issue_indexer", "DATADIR")
+	deprecatedSetting("indexer", "ISSUE_INDEXER_QUEUE_CONN_STR", "queue.issue_indexer", "CONN_STR")
+	deprecatedSetting("indexer", "ISSUE_INDEXER_QUEUE_BATCH_NUMBER", "queue.issue_indexer", "BATCH_LENGTH")
+	deprecatedSetting("indexer", "UPDATE_BUFFER_LEN", "queue.issue_indexer", "LENGTH")
 
 	Indexer.RepoIndexerEnabled = sec.Key("REPO_INDEXER_ENABLED").MustBool(false)
 	Indexer.RepoType = sec.Key("REPO_INDEXER_TYPE").MustString("bleve")
diff --git a/modules/setting/lfs.go b/modules/setting/lfs.go
index a4bbd3c3ff..7065ce6383 100644
--- a/modules/setting/lfs.go
+++ b/modules/setting/lfs.go
@@ -36,6 +36,8 @@ func newLFSService() {
 	storageType := lfsSec.Key("STORAGE_TYPE").MustString("")
 
 	// Specifically default PATH to LFS_CONTENT_PATH
+	//FIXME: DEPRECATED to be removed in v1.18.0
+	deprecatedSetting("server", "LFS_CONTENT_PATH", "lfs", "PATH")
 	lfsSec.Key("PATH").MustString(
 		sec.Key("LFS_CONTENT_PATH").String())
 
diff --git a/modules/setting/mailer.go b/modules/setting/mailer.go
index d7713f3b80..5da520171e 100644
--- a/modules/setting/mailer.go
+++ b/modules/setting/mailer.go
@@ -79,13 +79,15 @@ func newMailService() {
 	MailService.From = sec.Key("FROM").MustString(MailService.User)
 	MailService.EnvelopeFrom = sec.Key("ENVELOPE_FROM").MustString("")
 
+	// FIXME: DEPRECATED to be removed in v1.18.0
+	deprecatedSetting("mailer", "ENABLE_HTML_ALTERNATIVE", "mailer", "SEND_AS_PLAIN_TEXT")
 	if sec.HasKey("ENABLE_HTML_ALTERNATIVE") {
-		log.Warn("ENABLE_HTML_ALTERNATIVE is deprecated, use SEND_AS_PLAIN_TEXT")
 		MailService.SendAsPlainText = !sec.Key("ENABLE_HTML_ALTERNATIVE").MustBool(false)
 	}
 
+	// FIXME: DEPRECATED to be removed in v1.18.0
+	deprecatedSetting("mailer", "USE_SENDMAIL", "mailer", "MAILER_TYPE")
 	if sec.HasKey("USE_SENDMAIL") {
-		log.Warn("USE_SENDMAIL is deprecated, use MAILER_TYPE=sendmail")
 		if MailService.MailerType == "" && sec.Key("USE_SENDMAIL").MustBool(false) {
 			MailService.MailerType = "sendmail"
 		}
diff --git a/modules/setting/mirror.go b/modules/setting/mirror.go
index b0d5b2a4dc..e49393e39c 100644
--- a/modules/setting/mirror.go
+++ b/modules/setting/mirror.go
@@ -30,11 +30,12 @@ var (
 func newMirror() {
 	// Handle old configuration through `[repository]` `DISABLE_MIRRORS`
 	// - please note this was badly named and only disabled the creation of new pull mirrors
+	// FIXME: DEPRECATED to be removed in v1.18.0
+	deprecatedSetting("repository", "DISABLE_MIRRORS", "mirror", "ENABLED")
 	if Cfg.Section("repository").Key("DISABLE_MIRRORS").MustBool(false) {
-		log.Warn("Deprecated DISABLE_MIRRORS config is used, please change your config and use the options within the [mirror] section")
-		// TODO: enable on v1.17.0: log.Error("Deprecated fallback used, will be removed in v1.18.0")
 		Mirror.DisableNewPull = true
 	}
+
 	if err := Cfg.Section("mirror").MapTo(&Mirror); err != nil {
 		log.Fatal("Failed to map Mirror settings: %v", err)
 	}
diff --git a/modules/setting/queue.go b/modules/setting/queue.go
index 56a036aeef..cb86cbdfe0 100644
--- a/modules/setting/queue.go
+++ b/modules/setting/queue.go
@@ -107,51 +107,71 @@ func NewQueueService() {
 	Queue.SetName = sec.Key("SET_NAME").MustString("")
 
 	// Now handle the old issue_indexer configuration
+	// FIXME: DEPRECATED to be removed in v1.18.0
 	section := Cfg.Section("queue.issue_indexer")
 	directlySet := toDirectlySetKeysMap(section)
 	if !directlySet["TYPE"] && defaultType == "" {
-		switch Indexer.IssueQueueType {
-		case LevelQueueType:
+		switch typ := Cfg.Section("indexer").Key("ISSUE_INDEXER_QUEUE_TYPE").MustString(""); typ {
+		case "levelqueue":
 			_, _ = section.NewKey("TYPE", "level")
-		case ChannelQueueType:
+		case "channel":
 			_, _ = section.NewKey("TYPE", "persistable-channel")
-		case RedisQueueType:
+		case "redis":
 			_, _ = section.NewKey("TYPE", "redis")
 		case "":
 			_, _ = section.NewKey("TYPE", "level")
 		default:
-			log.Fatal("Unsupported indexer queue type: %v",
-				Indexer.IssueQueueType)
+			log.Fatal("Unsupported indexer queue type: %v", typ)
 		}
 	}
-	if !directlySet["LENGTH"] && Indexer.UpdateQueueLength != 0 {
-		_, _ = section.NewKey("LENGTH", strconv.Itoa(Indexer.UpdateQueueLength))
+	if !directlySet["LENGTH"] {
+		length := Cfg.Section("indexer").Key("UPDATE_BUFFER_LEN").MustInt(0)
+		if length != 0 {
+			_, _ = section.NewKey("LENGTH", strconv.Itoa(length))
+		}
 	}
-	if !directlySet["BATCH_LENGTH"] && Indexer.IssueQueueBatchNumber != 0 {
-		_, _ = section.NewKey("BATCH_LENGTH", strconv.Itoa(Indexer.IssueQueueBatchNumber))
+	if !directlySet["BATCH_LENGTH"] {
+		fallback := Cfg.Section("indexer").Key("ISSUE_INDEXER_QUEUE_BATCH_NUMBER").MustInt(0)
+		if fallback != 0 {
+			_, _ = section.NewKey("BATCH_LENGTH", strconv.Itoa(fallback))
+		}
 	}
-	if !directlySet["DATADIR"] && Indexer.IssueQueueDir != "" {
-		_, _ = section.NewKey("DATADIR", Indexer.IssueQueueDir)
+	if !directlySet["DATADIR"] {
+		queueDir := filepath.ToSlash(Cfg.Section("indexer").Key("ISSUE_INDEXER_QUEUE_DIR").MustString(""))
+		if queueDir != "" {
+			_, _ = section.NewKey("DATADIR", queueDir)
+		}
 	}
-	if !directlySet["CONN_STR"] && Indexer.IssueQueueConnStr != "" {
-		_, _ = section.NewKey("CONN_STR", Indexer.IssueQueueConnStr)
+	if !directlySet["CONN_STR"] {
+		connStr := Cfg.Section("indexer").Key("ISSUE_INDEXER_QUEUE_CONN_STR").MustString("")
+		if connStr != "" {
+			_, _ = section.NewKey("CONN_STR", connStr)
+		}
 	}
 
+	// FIXME: DEPRECATED to be removed in v1.18.0
+	// - will need to set default for [queue.*)] LENGTH appropriately though though
+
 	// Handle the old mailer configuration
-	handleOldLengthConfiguration("mailer", Cfg.Section("mailer").Key("SEND_BUFFER_LEN").MustInt(100))
+	handleOldLengthConfiguration("mailer", "mailer", "SEND_BUFFER_LEN", 100)
 
 	// Handle the old test pull requests configuration
 	// Please note this will be a unique queue
-	handleOldLengthConfiguration("pr_patch_checker", Cfg.Section("repository").Key("PULL_REQUEST_QUEUE_LENGTH").MustInt(1000))
+	handleOldLengthConfiguration("pr_patch_checker", "repository", "PULL_REQUEST_QUEUE_LENGTH", 1000)
 
 	// Handle the old mirror queue configuration
 	// Please note this will be a unique queue
-	handleOldLengthConfiguration("mirror", Cfg.Section("repository").Key("MIRROR_QUEUE_LENGTH").MustInt(1000))
+	handleOldLengthConfiguration("mirror", "repository", "MIRROR_QUEUE_LENGTH", 1000)
 }
 
 // handleOldLengthConfiguration allows fallback to older configuration. `[queue.name]` `LENGTH` will override this configuration, but
 // if that is left unset then we should fallback to the older configuration. (Except where the new length woul be <=0)
-func handleOldLengthConfiguration(queueName string, value int) {
+func handleOldLengthConfiguration(queueName, oldSection, oldKey string, defaultValue int) {
+	if Cfg.Section(oldSection).HasKey(oldKey) {
+		log.Error("Deprecated fallback for %s queue length `[%s]` `%s` present. Use `[queue.%s]` `LENGTH`. This will be removed in v1.18.0", queueName, queueName, oldSection, oldKey)
+	}
+	value := Cfg.Section(oldSection).Key(oldKey).MustInt(defaultValue)
+
 	// Don't override with 0
 	if value <= 0 {
 		return
diff --git a/modules/setting/setting.go b/modules/setting/setting.go
index 26eeda525f..3c8e009daa 100644
--- a/modules/setting/setting.go
+++ b/modules/setting/setting.go
@@ -387,6 +387,7 @@ var (
 		MaxTokenLength:             math.MaxInt16,
 	}
 
+	// FIXME: DEPRECATED to be removed in v1.18.0
 	U2F = struct {
 		AppID string
 	}{}
@@ -563,6 +564,12 @@ func LoadForTest(extraConfigs ...string) {
 	}
 }
 
+func deprecatedSetting(oldSection, oldKey, newSection, newKey string) {
+	if Cfg.Section(oldSection).HasKey(oldKey) {
+		log.Error("Deprecated fallback `[%s]` `%s` present. Use `[%s]` `%s` instead. This fallback will be removed in v1.18.0", oldSection, oldKey, newSection, newKey)
+	}
+}
+
 // loadFromConf initializes configuration context.
 // NOTE: do not print any log except error.
 func loadFromConf(allowEmpty bool, extraConfig string) {
@@ -1022,6 +1029,10 @@ func loadFromConf(allowEmpty bool, extraConfig string) {
 		UI.CustomEmojisMap[emoji] = ":" + emoji + ":"
 	}
 
+	// FIXME: DEPRECATED to be removed in v1.18.0
+	if Cfg.Section("U2F").HasKey("APP_ID") {
+		log.Error("Deprecated setting `[U2F]` `APP_ID` present. This fallback will be removed in v1.18.0")
+	}
 	sec = Cfg.Section("U2F")
 	U2F.AppID = sec.Key("APP_ID").MustString(strings.TrimSuffix(AppURL, "/"))
 }
diff --git a/modules/setting/task.go b/modules/setting/task.go
index d9329dbb76..c39d441108 100644
--- a/modules/setting/task.go
+++ b/modules/setting/task.go
@@ -4,14 +4,21 @@
 
 package setting
 
+// FIXME: DEPRECATED to be removed in v1.18.0
+// - will need to set default for [queue.task] LENGTH to 1000 though
 func newTaskService() {
 	taskSec := Cfg.Section("task")
 	queueTaskSec := Cfg.Section("queue.task")
-	switch taskSec.Key("QUEUE_TYPE").MustString(ChannelQueueType) {
-	case ChannelQueueType:
+
+	deprecatedSetting("task", "QUEUE_TYPE", "queue.task", "TYPE")
+	deprecatedSetting("task", "QUEUE_CONN_STR", "queue.task", "CONN_STR")
+	deprecatedSetting("task", "QUEUE_LENGTH", "queue.task", "LENGTH")
+
+	switch taskSec.Key("QUEUE_TYPE").MustString("channel") {
+	case "channel":
 		queueTaskSec.Key("TYPE").MustString("persistable-channel")
 		queueTaskSec.Key("CONN_STR").MustString(taskSec.Key("QUEUE_CONN_STR").MustString(""))
-	case RedisQueueType:
+	case "redis":
 		queueTaskSec.Key("TYPE").MustString("redis")
 		queueTaskSec.Key("CONN_STR").MustString(taskSec.Key("QUEUE_CONN_STR").MustString("addrs=127.0.0.1:6379 db=0"))
 	}
diff --git a/routers/web/auth/webauthn.go b/routers/web/auth/webauthn.go
index b9e8de2ac0..77b1bee18a 100644
--- a/routers/web/auth/webauthn.go
+++ b/routers/web/auth/webauthn.go
@@ -67,6 +67,7 @@ func WebAuthnLoginAssertion(ctx *context.Context) {
 		return
 	}
 
+	// FIXME: DEPRECATED appid is deprecated and is planned to be removed in v1.18.0
 	assertion, sessionData, err := wa.WebAuthn.BeginLogin((*wa.User)(user), webauthn.WithAssertionExtensions(protocol.AuthenticationExtensions{
 		"appid": setting.U2F.AppID,
 	}))