diff --git a/models/issue.go b/models/issue.go
index 1a4de26b3a..05eed6a78d 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -1953,6 +1953,11 @@ func deleteIssuesByRepoID(sess Engine, repoID int64) (attachmentPaths []string,
 		return
 	}
 
+	if _, err = sess.In("dependent_issue_id", deleteCond).
+		Delete(&Comment{}); err != nil {
+		return
+	}
+
 	var attachments []*Attachment
 	if err = sess.In("issue_id", deleteCond).
 		Find(&attachments); err != nil {
diff --git a/routers/repo/issue.go b/routers/repo/issue.go
index afe64c731f..6000d12b4f 100644
--- a/routers/repo/issue.go
+++ b/routers/repo/issue.go
@@ -969,8 +969,10 @@ func ViewIssue(ctx *context.Context) {
 			}
 		} else if comment.Type == models.CommentTypeRemoveDependency || comment.Type == models.CommentTypeAddDependency {
 			if err = comment.LoadDepIssueDetails(); err != nil {
-				ctx.ServerError("LoadDepIssueDetails", err)
-				return
+				if !models.IsErrIssueNotExist(err) {
+					ctx.ServerError("LoadDepIssueDetails", err)
+					return
+				}
 			}
 		} else if comment.Type == models.CommentTypeCode || comment.Type == models.CommentTypeReview {
 			comment.RenderedContent = string(markdown.Render([]byte(comment.Content), ctx.Repo.RepoLink,