openpyxl hangs loading an xlsx whose <dimension ref> is huge (A1:WVQ983110, typical of WPS-saved files)
Treat the file as a template and work at the XML level: unzip, read xl/worksheets/sheet1.xml, xl/styles.xml, xl/sharedStrings.xml, keep the original styles/theme, regenerate only the sheet XML with the needed rows (reusing the template's style ids), then zip it back:
import zipfile, re
z = zipfile.ZipFile('template.xlsx')
sheet = z.read('xl/worksheets/sheet1.xml').decode()
print(re.search(r'<dimension ref="([^"]+)"', sheet).group(1)) # diagnose
For read-only extraction, openpyxl's read_only=True mode with ws.reset_dimensions() is the documented escape hatch for wrong dimensions (not tested on this file).
Symptom
Loading a small (55-row) delivery-note template with openpyxl.load_workbook() never finishes / eats memory.
Cause
The sheet XML declares <dimension ref="A1:WVQ983110"/> (saved by WPS Office, with column styles spanning the whole sheet). openpyxl trusts the declared extent and column/row definitions, so it builds or iterates an enormous grid.
Verify
XML-level generation produced an .xlsx identical in look to the customer's template (checked visually with qlmanage -t -s 1600 -o outdir file.xlsx on macOS, which renders xlsx thumbnails without LibreOffice).
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