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By reviewing the logs, you should be able to determine the cause of the problem. If the error message is not clear, please provide the request and response in plain text. This will allow us to better understand the issue and assist in finding a resolution.
Also, please ensure that you followed the installation guide.
HTTP status 500
If the callback file is manually accessed via the browser, an error response will be output, and the HTTP status will be set to 500.
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