diff --git a/docs/troubleshooting/chart.md b/docs/troubleshooting/chart.md
index 7a89e877823..0a582309883 100644
--- a/docs/troubleshooting/chart.md
+++ b/docs/troubleshooting/chart.md
@@ -12,5 +12,5 @@ If any components output the `INTERNAL` error log, let us know the detail.
 
 ## Related Document
 
-- [Troubleshooting](../troubleshooting/troubleshooting.md)
+- [Operation Troubleshooting](../troubleshooting/operation-troubleshooting.md)
 
diff --git a/docs/troubleshooting/operation-troubleshooting.md b/docs/troubleshooting/operation-troubleshooting.md
new file mode 100644
index 00000000000..610c3bb3c95
--- /dev/null
+++ b/docs/troubleshooting/operation-troubleshooting.md
@@ -0,0 +1,57 @@
+# Operation troubleshooting
+
+This page introduces the popular troubleshooting for operating a Vald cluster.
+
+The [Flow chart](../troubleshooting/chart.md) helps you to find the root reason for your problem.
+Additionally, if you encounter some errors when using API, [API status code](../api/status.md) helps you, too.
+
+## Insert Operation
+
+### Vald Agent NGT crashed at the insert process.
+
+Let’s check your container limit of memory at first.
+Vald Agent requires memory for keeping indexing on memory.
+
+```bash
+kubectl describe statefulset vald-agent-ngt
+```
+
+If the limit memory is set, please remove it or update value larger.
+
+## Search Operation
+
+### Vald returns no search result.
+
+There are two possible reasons.
+
+1. Indexing has not finished in Vald Agent
+
+    Vald will search the nearest vectors of query from the indexing in Vald Agent.
+    If the indexing process is running, Vald Agent returns no search result.
+    
+    It will resolve when completed indexing instruction, like as `CreateIndex`.
+
+1. Too short timeout for searching
+
+    When the search timeout configuration is too short, Vald LB Gateway stops the searching process before getting search result from Vald Agent.
+
+In the sense of search operation, you can modify search timeout by [payload config](../api/search.md).
+
+<div class="notice">
+It is easy to find out which problem occurs by inspections the log of each Pod, like <a href="https://github.com/wercker/stern">stern</a>.
+</div>
+
+## Others
+
+### Vald Agent NGT crashed when initContainer.
+
+Vald Agent NGT requires an AVX2 processor for running.
+Please check your CPU information.
+
+---
+
+## Related Document
+
+- [Flow Chart](../troubleshooting/chart.md)
+- [API Status](../api/status.md)
+- [FAQ](../support/faq.md)
diff --git a/docs/troubleshooting/troubleshooting.md b/docs/troubleshooting/troubleshooting.md
deleted file mode 100644
index 90e10d33680..00000000000
--- a/docs/troubleshooting/troubleshooting.md
+++ /dev/null
@@ -1,36 +0,0 @@
-# Troubleshooting
-
-This page shows the troubleshooting for operating a Vald cluster.
-
-## Insert Operation
-
-### Vald Agent NGT crashed at the insert process.
-
-Let’s check your container limit of memory at first.
-Vald Agent requires memory for keeping indexing on memory.
-
-## Search Operation
-
-### Vald returns no search result.
-
-There are two possible reasons.
-
-1. Indexing has not finished in Vald Agent
-   - Vald will search the nearest vectors of query from the indexing in Vald Agent.
-     If the indexing process is running, Vald Agent returns no search result.
-1. Too short timeout for searching
-   - When the search timeout configuration is too short, Vald LB Gateway stops the searching process before getting search result from Vald Agent.
-
-## Others
-
-### Vald Agent NGT crashed when initContainer.
-
-Vald Agent NGT requires an AVX2 processor for running.
-Please check your CPU information.
-
----
-
-## Related Document
-
-- [Flow Chart](../troubleshooting/chart.md)
-- [FAQ](../support/faq.md)