What potential system environment factors on Windows could affect the display of Umlaute in FPDF compared to Linux?

The issue with displaying Umlaute in FPDF on Windows compared to Linux could be due to differences in character encoding settings. To solve this, you can explicitly set the character encoding in FPDF to UTF-8 before adding the text that contains Umlaute.

// Set character encoding to UTF-8
$pdf->SetFont('Arial', '', 12);
$pdf->SetTextColor(0, 0, 0);
$pdf->SetXY(10, 20);
$pdf->Write(0, iconv('UTF-8', 'windows-1252', 'Umlaute: äöü'));