Koha System

Common MARC Problems Before a Koha Migration

Common MARC record problems libraries should review before migrating to Koha.

May 12, 2026 3 min read

Catalogue data quality has a major effect on a Koha migration. Even when records can be imported, messy MARC data can affect search, display, reports, circulation setup, and staff confidence.

This article explains common MARC problems to review before importing records into Koha.

1. Missing or malformed Leader

The MARC Leader contains fixed-position information about the record. If it is missing, too short, or malformed, the record may not import cleanly or may behave unpredictably. MARCReady can help flag Leader issues for review.

2. Missing or incomplete 008 field

The 008 field contains fixed-length coded data. It can affect dates, language, material type, and retrieval. Common issues include: missing 008, 008 too short, blank or invalid date positions, missing language code, and material type coding that does not match the record.

3. Invalid indicators

Many MARC fields use indicators. Invalid indicators may affect display, indexing, or record interpretation. Common issues include blank indicators where values are expected, invalid characters, and inconsistent indicator patterns across similar records.

4. Empty subfields

Empty subfields add clutter and can cause confusing displays. A subfield code with no value may not always block import, but it is usually worth reviewing.

5. Encoding problems

Encoding problems are common in older exports. Symptoms include broken accented characters, strange symbols, question marks replacing characters, garbled punctuation, and incorrect apostrophes or quotation marks.

6. Duplicate fields

Some repeated fields are normal in MARC. Others may indicate export or conversion problems. Review duplicates such as: multiple title fields, duplicate ISBN fields with identical values, repeated control numbers, and repeated local fields with conflicting data.

7. ISBN problems

Common issues include: ISBN-10 and ISBN-13 mixed inconsistently, qualifiers stored inside the ISBN value, multiple ISBNs in one subfield, invalid check digits, and missing ISBNs for records that should have them.

8. Mixed bibliographic and item data

Bibliographic data describes the title. Item data describes the copy. Migration problems can occur when: barcodes are stored in notes fields, branch names are inconsistent, call numbers appear in multiple places, item types are missing, or multiple copies are represented as duplicate bibliographic records.

9. Local fields with unclear meaning

Many libraries use local fields, often in the 9XX range. Before migration, identify: which local fields should be preserved, which fields contain item data, which fields contain old system data that can be discarded, and which fields need mapping into Koha item or bibliographic fields.

10. Spreadsheet structure problems

Common spreadsheet problems include: one cell containing title, author, and publisher together; merged cells; blank rows; multiple titles in one row; multiple copies represented inconsistently; vague column headings; and patron or circulation data mixed with catalogue data.