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Excel Error Detective: Fix Formulas and Lookups
Find and fix the causes of Excel error values and lookups that return the wrong row. You will practise with the auditing tools, clean text that only looks like a number, write reliable XLOOKUP and INDEX/MATCH formulas, avoid hiding real bugs, and check a workbook before you share it. The course teac
Capable · 17 levels · 2 free · Created Oct 2026 · Professionally curated by levelupwith.com
What's inside
- Level 1: Read the Error ValueFree
Learn what each Excel error value (#N/A, #VALUE!, #REF!, #DIV/0!, #NAME?, #NUM!, #NULL!, #SPILL!, #CALC!) means and its usual causes; this course is independent of Microsoft and not endorsed by it. - Level 2: Trace the Cause with Excel's Auditing ToolsFree
Use Evaluate Formula, Trace Precedents and Trace Dependents, Error Checking, the Watch Window and F9 on part of a formula to find the step where a formula goes wrong. - Level 3: Fix References That Break When Copied
Diagnose formulas that return wrong results or #REF! after copying, and fix them with relative, absolute and mixed references. - Level 4: Numbers and Dates Stored as Text
Find numbers and dates that Excel stores as text and convert them so sums, comparisons and lookups work again. - Level 5: Stray Spaces and Hidden Characters
Detect stray, leading and non-breaking spaces and non-printing characters, then clean them with TRIM, CLEAN, SUBSTITUTE and VALUE. - Level 6: VLOOKUP's Traps
Find why VLOOKUP returns the wrong row or #N/A: approximate match by default, hard-coded column numbers, and no lookups to the left. - Level 7: XLOOKUP: Match Modes, Search Modes, if_not_found
Replace fragile lookups with XLOOKUP and use its match modes, search modes and if_not_found argument correctly. - Level 8: INDEX with MATCH
Build INDEX with MATCH lookups, including two-way lookups, as a flexible method that works in every Excel version. - Level 9: Duplicate Keys, Missing Keys, Other Workbooks
Handle lookups where keys are duplicated or missing, and lookups across tables and workbooks, including those that feed a pivot table. - Level 10: IFERROR and IFNA Without Hiding Bugs
Use IFERROR and IFNA to handle expected errors without covering up real mistakes in formulas or data. - Level 11: SUMIFS and COUNTIFS Criteria Pitfalls
Fix SUMIFS and COUNTIFS formulas that return 0 or wrong totals because of criteria syntax, mismatched ranges and data types. - Level 12: Manual Calculation, Circular Refs, Rounding
Diagnose results that do not update or look slightly wrong because of manual calculation, circular references and floating-point rounding. - Level 13: Dynamic Arrays and #SPILL!
Debug dynamic array formulas and spill ranges, including #SPILL! and #CALC! errors and implicit intersection with @. - Level 14: Tables and Structured References
Use Excel tables and structured references so formulas and lookups grow with the data instead of missing new rows. - Level 15: Readable Formulas with LET, Explained by Copilot
Rewrite long nested formulas with LET so each step can be named and checked, and ask Copilot in Excel to explain a formula then check its answer. - Level 16: Check a Workbook Before You Share It
Follow a numbered pre-send checklist to find errors, broken links, hidden content and calculation settings before sharing a workbook. - Level 17: Final Challenge: Repair the Broken Workbook Exam
Diagnose and repair a broken workbook that combines error values, dirty data, wrong lookups and hidden errors from the whole course.
Access
The first 2 levels are free with a free account. Every level, the podcast edition and the AI tutor come with All Access at £4.99/month or any Creator plan — see pricing.