TCPDF ERROR: Some data has been output, can't send PDF file - 不管

TCPDF is a popular open-source PHP library for generating PDF documents. However, sometimes you may encounter an error message like "TCPDF ERROR: Some data has been output, can't send PDF file - 不管" when trying to generate a PDF file.

What does this error message mean?

This error message usually indicates that some data has been output to the browser before the PDF file is generated, which prevents TCPDF from sending the PDF file to the browser. This can happen if there is any whitespace or output generated before calling the TCPDF library.

How to fix this error?

To fix this error, you need to make sure that no output is generated before calling the TCPDF library. A common solution is to use the PHP ob_start() function to buffer the output so that it can be discarded before generating the PDF file. Here is an example:

ob_start();

// generate PDF file with TCPDF

ob_end_clean();

// send PDF file to the browser

In the code above, ob_start() is used to start the output buffering, and ob_end_clean() is used to discard any output that may have been generated before calling the TCPDF library.

Conclusion

If you encounter the "TCPDF ERROR: Some data has been output, can't send PDF file - 不管" error message, it usually means that some output has been generated before calling the TCPDF library. By using output buffering, you can prevent this error and generate the PDF file without any issues.