Bad results in web interface and download not possible

[stweil]

The web interface (for example https://digi.bib.uni-mannheim.de/ocr-fileformat/) shows damaged results when converting from hOCR to ALTO2.0 or ALTO2.1:

<?xml version="1.0" encoding="utf-8"?>
<alto xmlns="http://www.loc.gov/standards˺lto/ns-v2#"
      xmlns:xlink="http://www.w3.org�/xlink"
      xmlns:xsi="http://www.w3.org�/XMLSchema-instance"
      xsi:schemaLocation="http://www.loc.gov/standards˺lto/ns-v2# http://www.loc.gov/standards˺lto/v2˺lto-2-0.xsd">
   <Description>
      <MeasurementUnit>pixel</MeasurementUnit>

It should look like this:

<?xml version="1.0" encoding="utf-8"?>
<alto xmlns="http://www.loc.gov/standards/alto/ns-v2#"
      xmlns:xlink="http://www.w3.org/1999/xlink"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.loc.gov/standards/alto/ns-v2# http://www.loc.gov/standards/alto/v2/alto-2-0.xsd">
   <Description>
      <MeasurementUnit>pixel</MeasurementUnit>

It is also not possible to download the result using the Download button.

According to user feedback, the web interface worked two months ago. In the meantime, we have upgraded the server software from Debian Jessie to Stretch. So the problem might be related to the change from PHP‌ 5.6 to PHP 7.0

[zuphilip]

The encoding problem is also shown in the screenshot which was created a year ago and the Dockerfile was using PHP 7.0 from the beginning.