diff --git a/custom/conf/app.example.ini b/custom/conf/app.example.ini
index c497f1be67..344f92be49 100644
--- a/custom/conf/app.example.ini
+++ b/custom/conf/app.example.ini
@@ -49,8 +49,9 @@ APP_NAME = ; Gitea: Git with a cup of tea
 ;; RUN_USER will automatically detect the current user - but you can set it here change it if you run locally
 RUN_USER = ; git
 ;;
-;; Application run mode, affects performance and debugging. Either "dev", "prod" or "test", default is "prod"
-RUN_MODE = ; prod
+;; Application run mode, affects performance and debugging: "dev" or "prod", default is "prod"
+;; Mode "dev" makes Gitea easier to develop and debug, values other than "dev" are treated as "prod" which is for production use.
+;RUN_MODE = prod
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
diff --git a/docs/content/doc/administration/config-cheat-sheet.en-us.md b/docs/content/doc/administration/config-cheat-sheet.en-us.md
index e7e482fc79..9bb2533dac 100644
--- a/docs/content/doc/administration/config-cheat-sheet.en-us.md
+++ b/docs/content/doc/administration/config-cheat-sheet.en-us.md
@@ -73,7 +73,7 @@ In addition there is _`StaticRootPath`_ which can be set as a built-in at build
 - `RUN_USER`: **_current OS username_/`$USER`/`$USERNAME` e.g. git**: The user Gitea will run as.
    This should be a dedicated system (non-user) account. Setting this incorrectly will cause Gitea
    to not start.
-- `RUN_MODE`: **prod**: Application run mode, affects performance and debugging. Either "dev", "prod" or "test".
+- `RUN_MODE`: **prod**: Application run mode, affects performance and debugging: `dev` or `prod`, default is `prod`. Mode `dev` makes Gitea easier to develop and debug, values other than `dev` are treated as `prod` which is for production use.
 
 ## Repository (`repository`)
 
diff --git a/modules/setting/setting.go b/modules/setting/setting.go
index 8f20ef0856..71cd9a12a9 100644
--- a/modules/setting/setting.go
+++ b/modules/setting/setting.go
@@ -251,7 +251,13 @@ func loadRunModeFrom(rootCfg ConfigProvider) {
 	if RunMode == "" {
 		RunMode = rootSec.Key("RUN_MODE").MustString("prod")
 	}
-	IsProd = strings.EqualFold(RunMode, "prod")
+
+	// non-dev mode is treated as prod mode, to protect users from accidentally running in dev mode if there is a typo in this value.
+	RunMode = strings.ToLower(RunMode)
+	if RunMode != "dev" {
+		RunMode = "prod"
+	}
+	IsProd = RunMode != "dev"
 
 	// check if we run as root
 	if os.Getuid() == 0 {
diff --git a/modules/templates/htmlrenderer.go b/modules/templates/htmlrenderer.go
index 21c268da78..e0cbc49ff4 100644
--- a/modules/templates/htmlrenderer.go
+++ b/modules/templates/htmlrenderer.go
@@ -97,6 +97,7 @@ func HTMLRenderer() *HTMLRender {
 }
 
 func ReloadHTMLTemplates() error {
+	log.Trace("Reloading HTML templates")
 	if err := htmlRender.CompileTemplates(); err != nil {
 		log.Error("Template error: %v\n%s", err, log.Stack(2))
 		return err
@@ -114,11 +115,11 @@ func initHTMLRenderer() {
 	htmlRender = &HTMLRender{}
 	if err := htmlRender.CompileTemplates(); err != nil {
 		p := &templateErrorPrettier{assets: AssetFS()}
-		wrapFatal(p.handleFuncNotDefinedError(err))
-		wrapFatal(p.handleUnexpectedOperandError(err))
-		wrapFatal(p.handleExpectedEndError(err))
-		wrapFatal(p.handleGenericTemplateError(err))
-		log.Fatal("HTMLRenderer CompileTemplates error: %v", err)
+		wrapTmplErrMsg(p.handleFuncNotDefinedError(err))
+		wrapTmplErrMsg(p.handleUnexpectedOperandError(err))
+		wrapTmplErrMsg(p.handleExpectedEndError(err))
+		wrapTmplErrMsg(p.handleGenericTemplateError(err))
+		wrapTmplErrMsg(fmt.Sprintf("CompileTemplates error: %v", err))
 	}
 
 	if !setting.IsProd {
@@ -128,11 +129,17 @@ func initHTMLRenderer() {
 	}
 }
 
-func wrapFatal(msg string) {
+func wrapTmplErrMsg(msg string) {
 	if msg == "" {
 		return
 	}
-	log.Fatal("Unable to compile templates, %s", msg)
+	if setting.IsProd {
+		// in prod mode, Gitea must have correct templates to run
+		log.Fatal("Gitea can't run with template errors: %s", msg)
+	} else {
+		// in dev mode, do not need to really exit, because the template errors could be fixed by developer soon and the templates get reloaded
+		log.Error("There are template errors but Gitea continues to run in dev mode: %s", msg)
+	}
 }
 
 type templateErrorPrettier struct {
diff --git a/modules/templates/mailer.go b/modules/templates/mailer.go
index ac1715fcd0..54d857a8f6 100644
--- a/modules/templates/mailer.go
+++ b/modules/templates/mailer.go
@@ -61,7 +61,10 @@ func Mailer(ctx context.Context) (*texttmpl.Template, *template.Template) {
 	bodyTemplates.Funcs(NewFuncMap())
 
 	assetFS := AssetFS()
-	refreshTemplates := func() {
+	refreshTemplates := func(firstRun bool) {
+		if !firstRun {
+			log.Trace("Reloading mail templates")
+		}
 		assetPaths, err := ListMailTemplateAssetNames(assetFS)
 		if err != nil {
 			log.Error("Failed to list mail templates: %v", err)
@@ -75,17 +78,21 @@ func Mailer(ctx context.Context) (*texttmpl.Template, *template.Template) {
 				continue
 			}
 			tmplName := strings.TrimPrefix(strings.TrimSuffix(assetPath, ".tmpl"), "mail/")
-			log.Trace("Adding mail template %s: %s by %s", tmplName, assetPath, layerName)
+			if firstRun {
+				log.Trace("Adding mail template %s: %s by %s", tmplName, assetPath, layerName)
+			}
 			buildSubjectBodyTemplate(subjectTemplates, bodyTemplates, tmplName, content)
 		}
 	}
 
-	refreshTemplates()
+	refreshTemplates(true)
 
 	if !setting.IsProd {
 		// Now subjectTemplates and bodyTemplates are both synchronized
 		// thus it is safe to call refresh from a different goroutine
-		go assetFS.WatchLocalChanges(ctx, refreshTemplates)
+		go assetFS.WatchLocalChanges(ctx, func() {
+			refreshTemplates(false)
+		})
 	}
 
 	return subjectTemplates, bodyTemplates