HTTP Status 500 - Request processing failed; nested exception is org.springframework.web.multipart.MultipartException: Could not parse multipart servlet request; nested exception is java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$FileSizeLimitExceededException: The field filestream exceeds its maximum permitted size of 1048576 bytes.

The error you are encountering is a `HTTP Status 500` error indicating that a request processing failure occurred due to a `MultipartException` during the handling of a multipart servlet request. The specific cause is an `IllegalStateException` thrown because the uploaded file (`filestream`) exceeds the maximum permitted file size limit.

Here are the key points to understand about the error and how to resolve it:

Cause of the Error: The error arises because the uploaded file exceeds the maximum permitted file size set in your application's configuration. The exception specifically points to the file size limit set for file uploads, which is currently set at 1,048,576 bytes (1 MB).

Configuration for File Upload: In Spring applications, the file upload size limit is typically controlled by settings in the `multipart` configuration. The `FileSizeLimitExceededException` is a type of exception that is triggered when an uploaded file exceeds the configured size limit.

Increasing File Size Limit: You can increase the maximum permitted file size for file uploads by adjusting the relevant configuration in your application. Here are a few common places where you can set the file size limit:

    - Spring Boot: If you are using Spring Boot, you can increase the file size limit by configuring properties in `application.properties` or `application.yml`:

   - `spring.servlet.multipart.max-file-size=10MB`  # Set the maximum file size to 10 MB

 - `spring.servlet.multipart.max-request-size=10MB`  # Set the maximum request size to 10 MB

    - Servlet Configuration: If you are not using Spring Boot, you may need to adjust the file size limit in your `web.xml` configuration file, or in your servlet configuration:

        - For Apache Tomcat, you might configure the `maxFileSize` attribute in the `MultipartConfig` annotation of the servlet:

            ```java

            @MultipartConfig(maxFileSize = 10 * 1024 * 1024)  // 10 MB

           ```

        - Alternatively, you can use `web.xml` to configure the file size limits for your servlets.

•  Locate the `web.xml` file for your Tomcat server. It is typically found in the `WEB-INF` directory of your web application.
•  Open the `web.xml` file in a text editor.
•  Find the `<multipart-config>` element in the `web.xml` file. It might look something like this:

```xml
<multipart-config>
<max-file-size>1048576</max-file-size>
<max-request-size>1048576</max-request-size>
<file-size-threshold>0</file-size-threshold>
</multipart-config>
```

• Modify the `<max-file-size>` and `<max-request-size>` values to your desired maximum file size. For example, to allow a maximum file size of 10 MB, you can set them to 10485760:

```xml
<multipart-config>
<max-file-size>10485760</max-file-size>
<max-request-size>10485760</max-request-size>
<file-size-threshold>0</file-size-threshold>
</multipart-config>

```

• Save the `web.xml` file.

4. Restart Your Application: After making the changes to your application's configuration, be sure to restart your application for the new settings to take effect.

By increasing the file size limit as per your application's requirements, you should be able to resolve the `FileSizeLimitExceededException` and allow larger file uploads in your application.