Troubleshooting: add A Request Error Occurs After Filtering or Search… (

#5623) (#5650)

concepts/80 Troubleshooting/05 DataGrid and TreeList Issues/15 A Request Error Occurs After Filtering or Searching.md

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+This topic addresses multiple request errors that may occur in your application. To check an error code, follow the steps below:
+
+1. Obtain a URL link generated by the problematic data query in the browser [network tab](/Documentation/Guide/Troubleshooting/A_Drop-Down_Editor_Does_Not_Show_Data/#AspNetDatacreateStore_Method_Specifics). Paste the URL in a new browser tab.
+
+2. Enable exceptions on the server to see a detailed error message. In ASP.NET, you can obtain an exception call stack. Refer to the following help topic for more information: [How to obtain an exception call stack](https://docs.devexpress.com/GeneralInformation/403685/support-debug-troubleshooting/obtain-exception-call-stack).
+
+[DevExtreme.AspNet.Data](https://github.com/DevExpress/DevExtreme.AspNet.Data#devextreme-aspnet-data) sends load parameters (skip, take, filter, and group) in the browser URL. As a result, an error may occur if a string with parameters is too long and cannot be processed on the server. Refer to the following article for more information: [Request Limits](https://docs.microsoft.com/en-us/iis/configuration/system.webserver/security/requestfiltering/requestlimits/). 
+
+The following errors may occur:
+
+- `Query string is too long`
+- `Request URI is too long`
+- `Maximum request length exceeded`
+- `404`
+- `404.15`
+- The `object XMLHttpRequest` error occurs once you define total and group summaries in DataGrid.
+- Filtering by `Search Panel` does not work if the component has a lookup column.
+- Filtering by `Search Panel` does not work if the component has more than 20 columns.
+- Selection does not work if [selection.deferred](/Documentation/ApiReference/UI_Components/dxDataGrid/Configuration/selection/#deferred) is `true`.
+
+If you receive one of the errors above, one of the following solutions may help you resolve it:
+
+- Increase the maximum query string length in your backend configuration file.
+Note that browsers also impose their own restrictions on the maximum URL length: [What is the maximum length of a URL in different browsers?](https://stackoverflow.com/questions/417142/what-is-the-maximum-length-of-a-url-in-different-browsers).
+
+- Use `POST` requests instead of `GET` requests. Set the `LoadMethod` option to `POST` and change the `LoadAction` implementation as follows:
+
+    ---
+    ##### jQuery
+
+        <!-- tab: index.js-->
+        $("#grid").dxDataGrid({     
+            dataSource: DevExpress.data.AspNet.createStore({
+                key: "keyFieldName",
+                loadUrl: url,
+                loadMethod: "POST",
+            }),
+            // ...
+        });
+
+    ##### Angular
+
+        <!-- tab: app.component.ts -->
+        import { createStore } from 'devextreme-aspnet-data-nojquery';
+
+        const dataSource = createStore({
+            key: "keyFieldName",
+            loadUrl: urlHere,
+            loadMethod: "Post",
+            // ...
+        });
+
+    ##### Vue
+
+        <!-- tab: App.vue -->
+        <template>
+            <!-- ... -->
+        </template>
+
+        <script>
+        import { createStore } from 'devextreme-aspnet-data-nojquery';
+
+        const dataSource = createStore({
+            key: "keyFieldName",
+            loadUrl: urlHere,
+            loadMethod: "Post",
+            // ...
+        });
+        </script>
+
+    ##### React
+
+        <!-- tab: App.js -->
+        import { createStore } from 'devextreme-aspnet-data-nojquery';
+
+        const dataSource = createStore({
+            key: "keyFieldName",
+            loadUrl: urlHere,
+            loadMethod: "Post",
+            // ...
+        });
+
+    ---
+
+    As `POST` request size becomes large after these changes, you may need to increase the `Content-Length` value in the server configuration file.