Have you ever encountered the dreaded System.Text.Json.JsonException: The input does not contain any JSON tokens error in your Blazor application? If so, you’re not alone! This error can be quite confusing and frustrating to deal with, but fear not – we’ve got you covered. In this blog post, we’ll walk you through the possible causes of this error and provide some solutions to help you get back on track.
Understanding the error message
The full error message you might encounter is:
System.Text.Json.JsonException: The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. Path: $ | LineNumber: 0 | BytePositionInLine: 0.
This error typically occurs when you’re trying to deserialize an empty or invalid JSON string, and the parser is unable to find any valid JSON tokens to process. In other words, the JSON data you’re trying to work with is either missing or malformed.
Possible causes and solutions
1. Invalid or empty JSON response
One common cause of this error is receiving an empty or invalid JSON response from your API endpoint. This could be due to an incorrect API URL, a misspelled endpoint, or even a server-side issue causing the API to return an empty response. To fix this issue, double-check your API endpoint and ensure it is returning valid JSON data.
2. Incorrect use of JsonObject.Parse
In some cases, you might be using JsonObject.Parse() on an empty JSON string, which would throw the exception in question. To resolve this, simply add a conditional check before parsing the JSON data:
var json = await response.Content.ReadAsStringAsync(); var result = string.IsNullOrEmpty(json) ? null : JsonObject.Parse(json);
This will ensure that you’re only attempting to parse the JSON data if it exists, preventing the error from occurring.
3. Issues with secrets.json file
If you’re using the secrets.json file for managing user secrets in your application, an invalid or empty JSON object in the file could also trigger this error. Make sure your secrets.json file contains a valid JSON object, even if it’s just an empty one:
{
}
You can edit the secrets.json file via Visual Studio by right-clicking your project in the Solution Explorer and selecting “Manage User Secrets.”
Wrapping up
Encountering the System.Text.Json.JsonException: The input does not contain any JSON tokens error can be frustrating, but with a little bit of investigation and the solutions provided in this blog post, you should be able to resolve the issue and get your Blazor application up and running smoothly once again. Remember, the key is to ensure that you’re working with valid JSON data and handling it correctly within your application. Happy coding!
