1 files changed, 18 insertions, 0 deletions
diff --git a/routers/repo/issue_watch.go b/routers/repo/issue_watch.go
index c6a436801a..eae663495a 100644
--- a/routers/repo/issue_watch.go
+++ b/routers/repo/issue_watch.go
@@ -11,6 +11,7 @@ import (
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/log"
 )
 
 // IssueWatch sets issue watching
@@ -21,6 +22,23 @@ func IssueWatch(ctx *context.Context) {
 	}
 
 	if !ctx.IsSigned || (ctx.User.ID != issue.PosterID && !ctx.Repo.CanReadIssuesOrPulls(issue.IsPull)) {
+		if log.IsTrace() {
+			if ctx.IsSigned {
+				issueType := "issues"
+				if issue.IsPull {
+					issueType = "pulls"
+				}
+				log.Trace("Permission Denied: User %-v not the Poster (ID: %d) and cannot read %s in Repo %-v.\n"+
+					"User in Repo has Permissions: %-+v",
+					ctx.User,
+					log.NewColoredIDValue(issue.PosterID),
+					issueType,
+					ctx.Repo.Repository,
+					ctx.Repo.Permission)
+			} else {
+				log.Trace("Permission Denied: Not logged in")
+			}
+		}
 		ctx.Error(403)
 		return
 	}