I think the error that you have can be because the format of a CSV file doesn't match the expected schema, particularly during parsing operations. This can happen if the actual data contains more columns than expected or if the delimiter isn't consistently applied across the data.
Since you mentioned the file reads correctly in other tools, it might still contain special characters or extra quotes that are not properly escaped, which could be interpreted incorrectly by the pandas
parser.
You can modify your read operation to handle potential parsing errors better or to skip over problematic lines or to issue warnings that can help identify the exact issue.
df = pd.read_csv(BytesIO(attachment.content), sep='|', error_bad_lines=False, warn_bad_lines=True)
Then add additional logging right before the parsing step to output the raw data of the first few lines.
raw_content = BytesIO(attachment.content)
print(raw_content.getvalue()[:500]) # print first 500 characters of the file
df = pd.read_csv(raw_content, sep='|')