> ## Documentation Index
> Fetch the complete documentation index at: https://docs.spn.wtf/llms.txt
> Use this file to discover all available pages before exploring further.

# Troubleshooting

> Common errors and how to fix them

## Missing Columns Error

**Symptom:** The app reports that a required column is missing.

**Fix:**

1. Open your Excel file and check the column headers
2. Ensure headers exactly match what the company's SOP expects
3. Look for **hidden trailing spaces** in headers — these are a common cause of false mismatches
4. Re-upload after correcting the headers

***

## CSV Encoding Errors

**Symptom:** The app fails to read a `.csv` file.

**Fix:**

* The app natively supports UTF-8 and automatically falls back to `latin-1`
* If both fail, save the file locally as `.xlsx` and re-upload

***

## Missing GSTINs or HSN Codes

**Symptom:** The preview shows a warning about missing GSTINs or HSN codes.

**Cause:** The Party Code or Material Code in the Bill Details was not found in the uploaded B2B Master or Material Master files.

**Result:** Affected rows will have blank HSN fields or be marked `UNREGISTERED` in the final output. This is expected behaviour — no data is lost.

**Fix:** Verify that the Master files are up to date and contain all Party/Material Codes present in the Bill Details.

***

## Row Count Mismatch

**Symptom:** Processing fails with a row cardinality error.

**Cause:** The output row count does not match the input Bill Details — this indicates an unintended duplication somewhere in the lookup logic.

**Fix:** Check for duplicate keys in your B2B Master or Material Master files. Each Party Code and Material Code must be unique.