diff --git a/modules/actions/workflows.go b/modules/actions/workflows.go
index 4ac06def4d5a1..83bbfa3a1b87d 100644
--- a/modules/actions/workflows.go
+++ b/modules/actions/workflows.go
@@ -107,6 +107,13 @@ func GetEventsFromContent(content []byte) ([]*jobparser.Event, error) {
 	return events, nil
 }
 
+// ValidateWorkflowContent catches structural errors (e.g. blank lines in run: | blocks)
+// that model.ReadWorkflow alone does not detect.
+func ValidateWorkflowContent(content []byte) error {
+	_, err := jobparser.Parse(content)
+	return err
+}
+
 func DetectWorkflows(
 	gitRepo *git.Repository,
 	commit *git.Commit,
@@ -129,6 +136,9 @@ func DetectWorkflows(
 
 		// one workflow may have multiple events
 		events, err := GetEventsFromContent(content)
+		if err == nil {
+			err = ValidateWorkflowContent(content)
+		}
 		if err != nil {
 			log.Warn("ignore invalid workflow %q: %v", entry.Name(), err)
 			continue
@@ -173,6 +183,9 @@ func DetectScheduledWorkflows(gitRepo *git.Repository, commit *git.Commit) ([]*D
 
 		// one workflow may have multiple events
 		events, err := GetEventsFromContent(content)
+		if err == nil {
+			err = ValidateWorkflowContent(content)
+		}
 		if err != nil {
 			log.Warn("ignore invalid workflow %q: %v", entry.Name(), err)
 			continue
diff --git a/routers/web/repo/actions/actions.go b/routers/web/repo/actions/actions.go
index 988d2d0a993b9..7d373c79ed6b7 100644
--- a/routers/web/repo/actions/actions.go
+++ b/routers/web/repo/actions/actions.go
@@ -151,6 +151,11 @@ func prepareWorkflowTemplate(ctx *context.Context, commit *git.Commit) (workflow
 			workflows = append(workflows, workflow)
 			continue
 		}
+		if err := actions.ValidateWorkflowContent(content); err != nil {
+			workflow.ErrMsg = ctx.Locale.TrString("actions.runs.invalid_workflow_helper", err.Error())
+			workflows = append(workflows, workflow)
+			continue
+		}
 		workflow.Workflow = wf
 		// The workflow must contain at least one job without "needs". Otherwise, a deadlock will occur and no jobs will be able to run.
 		hasJobWithoutNeeds := false
diff --git a/routers/web/repo/view_file.go b/routers/web/repo/view_file.go
index 3ae0dab25b8a3..65fcb8adba233 100644
--- a/routers/web/repo/view_file.go
+++ b/routers/web/repo/view_file.go
@@ -25,8 +25,6 @@ import (
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/services/context"
 	issue_service "code.gitea.io/gitea/services/issue"
-
-	"github.com/nektos/act/pkg/model"
 )
 
 func prepareLatestCommitInfo(ctx *context.Context) bool {
@@ -184,8 +182,7 @@ func prepareFileView(ctx *context.Context, entry *git.TreeEntry) {
 		if err != nil {
 			log.Error("actions.GetContentFromEntry: %v", err)
 		}
-		_, workFlowErr := model.ReadWorkflow(bytes.NewReader(content))
-		if workFlowErr != nil {
+		if workFlowErr := actions.ValidateWorkflowContent(content); workFlowErr != nil {
 			ctx.Data["FileError"] = ctx.Locale.Tr("actions.runs.invalid_workflow_helper", workFlowErr.Error())
 		}
 	} else if issue_service.IsCodeOwnerFile(ctx.Repo.TreePath) {