diff --git a/routers/web/repo/fork.go b/routers/web/repo/fork.go
index 79f033659b..9f5cda10c2 100644
--- a/routers/web/repo/fork.go
+++ b/routers/web/repo/fork.go
@@ -151,7 +151,7 @@ func ForkPost(ctx *context.Context) {
 	ctx.Data["ContextUser"] = ctxUser
 
 	if ctx.HasError() {
-		ctx.HTML(http.StatusOK, tplFork)
+		ctx.JSONError(ctx.GetErrMsg())
 		return
 	}
 
@@ -159,12 +159,12 @@ func ForkPost(ctx *context.Context) {
 	traverseParentRepo := forkRepo
 	for {
 		if !repository.CanUserForkBetweenOwners(ctxUser.ID, traverseParentRepo.OwnerID) {
-			ctx.RenderWithErr(ctx.Tr("repo.settings.new_owner_has_same_repo"), tplFork, &form)
+			ctx.JSONError(ctx.Tr("repo.settings.new_owner_has_same_repo"))
 			return
 		}
 		repo := repo_model.GetForkedRepo(ctx, ctxUser.ID, traverseParentRepo.ID)
 		if repo != nil {
-			ctx.Redirect(ctxUser.HomeLink() + "/" + url.PathEscape(repo.Name))
+			ctx.JSONRedirect(ctxUser.HomeLink() + "/" + url.PathEscape(repo.Name))
 			return
 		}
 		if !traverseParentRepo.IsFork {
@@ -201,26 +201,26 @@ func ForkPost(ctx *context.Context) {
 		case repo_model.IsErrReachLimitOfRepo(err):
 			maxCreationLimit := ctxUser.MaxCreationLimit()
 			msg := ctx.TrN(maxCreationLimit, "repo.form.reach_limit_of_creation_1", "repo.form.reach_limit_of_creation_n", maxCreationLimit)
-			ctx.RenderWithErr(msg, tplFork, &form)
+			ctx.JSONError(msg)
 		case repo_model.IsErrRepoAlreadyExist(err):
-			ctx.RenderWithErr(ctx.Tr("repo.settings.new_owner_has_same_repo"), tplFork, &form)
+			ctx.JSONError(ctx.Tr("repo.settings.new_owner_has_same_repo"))
 		case repo_model.IsErrRepoFilesAlreadyExist(err):
 			switch {
 			case ctx.IsUserSiteAdmin() || (setting.Repository.AllowAdoptionOfUnadoptedRepositories && setting.Repository.AllowDeleteOfUnadoptedRepositories):
-				ctx.RenderWithErr(ctx.Tr("form.repository_files_already_exist.adopt_or_delete"), tplFork, form)
+				ctx.JSONError(ctx.Tr("form.repository_files_already_exist.adopt_or_delete"))
 			case setting.Repository.AllowAdoptionOfUnadoptedRepositories:
-				ctx.RenderWithErr(ctx.Tr("form.repository_files_already_exist.adopt"), tplFork, form)
+				ctx.JSONError(ctx.Tr("form.repository_files_already_exist.adopt"))
 			case setting.Repository.AllowDeleteOfUnadoptedRepositories:
-				ctx.RenderWithErr(ctx.Tr("form.repository_files_already_exist.delete"), tplFork, form)
+				ctx.JSONError(ctx.Tr("form.repository_files_already_exist.delete"))
 			default:
-				ctx.RenderWithErr(ctx.Tr("form.repository_files_already_exist"), tplFork, form)
+				ctx.JSONError(ctx.Tr("form.repository_files_already_exist"))
 			}
 		case db.IsErrNameReserved(err):
-			ctx.RenderWithErr(ctx.Tr("repo.form.name_reserved", err.(db.ErrNameReserved).Name), tplFork, &form)
+			ctx.JSONError(ctx.Tr("repo.form.name_reserved", err.(db.ErrNameReserved).Name))
 		case db.IsErrNamePatternNotAllowed(err):
-			ctx.RenderWithErr(ctx.Tr("repo.form.name_pattern_not_allowed", err.(db.ErrNamePatternNotAllowed).Pattern), tplFork, &form)
+			ctx.JSONError(ctx.Tr("repo.form.name_pattern_not_allowed", err.(db.ErrNamePatternNotAllowed).Pattern))
 		case errors.Is(err, user_model.ErrBlockedUser):
-			ctx.RenderWithErr(ctx.Tr("repo.fork.blocked_user"), tplFork, form)
+			ctx.JSONError(ctx.Tr("repo.fork.blocked_user"))
 		default:
 			ctx.ServerError("ForkPost", err)
 		}
@@ -228,5 +228,5 @@ func ForkPost(ctx *context.Context) {
 	}
 
 	log.Trace("Repository forked[%d]: %s/%s", forkRepo.ID, ctxUser.Name, repo.Name)
-	ctx.Redirect(ctxUser.HomeLink() + "/" + url.PathEscape(repo.Name))
+	ctx.JSONRedirect(ctxUser.HomeLink() + "/" + url.PathEscape(repo.Name))
 }
diff --git a/templates/repo/pulls/fork.tmpl b/templates/repo/pulls/fork.tmpl
index adf9e250c1..0d775ed6a0 100644
--- a/templates/repo/pulls/fork.tmpl
+++ b/templates/repo/pulls/fork.tmpl
@@ -6,7 +6,7 @@
 		</h3>
 		<div class="ui attached segment">
 			{{template "base/alert" .}}
-			<form class="ui form left-right-form" action="{{.Link}}" method="post">
+			<form class="ui form form-fetch-action left-right-form" action="{{.Link}}" method="post">
 				{{.CsrfTokenHtml}}
 				<div class="inline required field {{if .Err_Owner}}error{{end}}">
 					<label>{{ctx.Locale.Tr "repo.owner"}}</label>
diff --git a/tests/integration/repo_fork_test.go b/tests/integration/repo_fork_test.go
index a7010af14a..db2caaf6ca 100644
--- a/tests/integration/repo_fork_test.go
+++ b/tests/integration/repo_fork_test.go
@@ -15,6 +15,7 @@ import (
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/structs"
+	"code.gitea.io/gitea/modules/test"
 	org_service "code.gitea.io/gitea/services/org"
 	"code.gitea.io/gitea/tests"
 
@@ -51,7 +52,8 @@ func testRepoFork(t *testing.T, session *TestSession, ownerName, repoName, forkO
 		"repo_name":          forkRepoName,
 		"fork_single_branch": forkBranch,
 	})
-	session.MakeRequest(t, req, http.StatusSeeOther)
+	resp = session.MakeRequest(t, req, http.StatusOK)
+	assert.Equal(t, fmt.Sprintf("/%s/%s", forkOwnerName, forkRepoName), test.RedirectURL(resp))
 
 	// Step4: check the existence of the forked repo
 	req = NewRequestf(t, "GET", "/%s/%s", forkOwnerName, forkRepoName)