diff --git a/docs/content/contributing/guidelines-backend.en-us.md b/docs/content/contributing/guidelines-backend.en-us.md
index 084b3886e84..3159a5ff7d1 100644
--- a/docs/content/contributing/guidelines-backend.en-us.md
+++ b/docs/content/contributing/guidelines-backend.en-us.md
@@ -101,6 +101,10 @@ i.e. `services/user`, `models/repository`.
 Since there are some packages which use the same package name, it is possible that you find packages like `modules/user`, `models/user`, and `services/user`. When these packages are imported in one Go file, it's difficult to know which package we are using and if it's a variable name or an import name. So, we always recommend to use import aliases. To differ from package variables which are commonly in camelCase, just use **snake_case** for import aliases.
 i.e. `import user_service "code.gitea.io/gitea/services/user"`
 
+### Implementing `io.Closer`
+
+If a type implements `io.Closer`, calling `Close` multiple times must not fail or `panic` but return an error or `nil`.
+
 ### Important Gotchas
 
 - Never write `x.Update(exemplar)` without an explicit `WHERE` clause:
diff --git a/modules/git/blame.go b/modules/git/blame.go
index 64095a218a3..69e1b08f93b 100644
--- a/modules/git/blame.go
+++ b/modules/git/blame.go
@@ -115,6 +115,10 @@ func (r *BlameReader) NextPart() (*BlamePart, error) {
 
 // Close BlameReader - don't run NextPart after invoking that
 func (r *BlameReader) Close() error {
+	if r.bufferedReader == nil {
+		return nil
+	}
+
 	err := <-r.done
 	r.bufferedReader = nil
 	_ = r.reader.Close()
diff --git a/modules/git/repo_base_gogit.go b/modules/git/repo_base_gogit.go
index 9270bb70f07..3ca5eb36c6e 100644
--- a/modules/git/repo_base_gogit.go
+++ b/modules/git/repo_base_gogit.go
@@ -88,16 +88,17 @@ func OpenRepository(ctx context.Context, repoPath string) (*Repository, error) {
 }
 
 // Close this repository, in particular close the underlying gogitStorage if this is not nil
-func (repo *Repository) Close() (err error) {
+func (repo *Repository) Close() error {
 	if repo == nil || repo.gogitStorage == nil {
-		return
+		return nil
 	}
 	if err := repo.gogitStorage.Close(); err != nil {
 		gitealog.Error("Error closing storage: %v", err)
 	}
+	repo.gogitStorage = nil
 	repo.LastCommitCache = nil
 	repo.tagCache = nil
-	return
+	return nil
 }
 
 // GoGitRepo gets the go-git repo representation
diff --git a/modules/git/repo_base_nogogit.go b/modules/git/repo_base_nogogit.go
index 8c6eae5897e..86b6a935677 100644
--- a/modules/git/repo_base_nogogit.go
+++ b/modules/git/repo_base_nogogit.go
@@ -103,7 +103,7 @@ func (repo *Repository) CatFileBatchCheck(ctx context.Context) (WriteCloserError
 	}
 }
 
-func (repo *Repository) Close() (err error) {
+func (repo *Repository) Close() error {
 	if repo == nil {
 		return nil
 	}
@@ -123,5 +123,5 @@ func (repo *Repository) Close() (err error) {
 	}
 	repo.LastCommitCache = nil
 	repo.tagCache = nil
-	return err
+	return nil
 }
diff --git a/modules/indexer/internal/bleve/indexer.go b/modules/indexer/internal/bleve/indexer.go
index ce06b5afcb7..01e53ca6360 100644
--- a/modules/indexer/internal/bleve/indexer.go
+++ b/modules/indexer/internal/bleve/indexer.go
@@ -92,7 +92,7 @@ func (i *Indexer) Ping(_ context.Context) error {
 }
 
 func (i *Indexer) Close() {
-	if i == nil {
+	if i == nil || i.Indexer == nil {
 		return
 	}
 
diff --git a/modules/indexer/internal/meilisearch/indexer.go b/modules/indexer/internal/meilisearch/indexer.go
index b037249d432..f4004849c1d 100644
--- a/modules/indexer/internal/meilisearch/indexer.go
+++ b/modules/indexer/internal/meilisearch/indexer.go
@@ -87,8 +87,5 @@ func (i *Indexer) Close() {
 	if i == nil {
 		return
 	}
-	if i.Client == nil {
-		return
-	}
 	i.Client = nil
 }
diff --git a/modules/util/filebuffer/file_backed_buffer.go b/modules/util/filebuffer/file_backed_buffer.go
index 6b07bd04138..739543e2977 100644
--- a/modules/util/filebuffer/file_backed_buffer.go
+++ b/modules/util/filebuffer/file_backed_buffer.go
@@ -149,6 +149,7 @@ func (b *FileBackedBuffer) Close() error {
 	if b.file != nil {
 		err := b.file.Close()
 		os.Remove(b.file.Name())
+		b.file = nil
 		return err
 	}
 	return nil