--- sidebar_position: 2 title: Troubleshooting hide_table_of_contents: true --- import current from '/version.js'; import CodeBlock from '@theme/CodeBlock'; Here are some common errors and their resolutions. This is not comprehensive. The [issue tracker](https://git.sheetjs.com/SheetJS/sheetjs/issues) has a wealth of information and user-contributed examples. **Many of these errors have been fixed in newer releases!** Ensure that the latest version of the library is being used. Some legacy endpoints are out of date. [Review the Installation instructions.](/docs/getting-started/installation) If issues are not covered in the docs or the issue tracker, or if a solution is not discussed in the documentation, we would appreciate a bug report. :::info Special Thanks Special thanks to the early adopters and users for discovering and sharing many workarounds and solutions! ::: ## Errors #### Uncaught TypeError: Cannot read property of undefined Errors include ``` Uncaught TypeError: Cannot read property 'read' of undefined Uncaught TypeError: Cannot read property 'writeFile' of undefined Uncaught TypeError: Cannot read property 'utils' of undefined ``` The root cause is an undefined `XLSX` variable. This usually means the library was not properly loaded. [Review the Installation instructions.](/docs/getting-started/installation) If the error shows up while using the latest version, projects may require other configuration or loading strategies.
Upgrade Note (click to show) Older versions of the library only shipped with CommonJS and standalone script. Webpack and other bundlers supported CommonJS dependencies with default import: ```js // old way import XLSX from "xlsx"; ``` Newer versions of the library ship with an ESM build. When upgrading, imports should be updated: ```js // new way import * as XLSX from "xlsx"; import * as cptable from "xlsx/dist/cpexcel.full.mjs"; XLSX.set_cptable(cptable); ``` Newer releases support tree shaking, and special methods like `writeFileXLSX` help reduce bundle size. [The bundler note](/docs/getting-started/installation/frameworks) explains in further detail.
#### "Aw Snap!" or "Oops, an error has occurred!" Browsers have strict memory limits and large spreadsheets can exceed the limits. For large worksheets, use [dense worksheets](/docs/csf/sheet#dense-mode): ```js var wb = XLSX.read(data, {dense: true}); // creates a dense-mode sheet XLSX.writeFile(data, "large.xlsx"); // writeFile can handle dense-mode sheets ``` When processing very large files is a must, consider running processes in the server with NodeJS or some other server-side technology. If the files are small, please [report to our issue tracker](https://git.sheetjs.com/sheetjs/sheetjs/issues) :::info pass Sparse worksheets historically were more performant in small sheets. Due to a [2014 bug in V8](https://bugs.chromium.org/p/v8/issues/detail?id=3175) and a [2017 regression in V8](https://bugs.chromium.org/p/v8/issues/detail?id=6696) (the JavaScript engine powering Node and Chrome), large sparse worksheets will crash the web browser. ::: #### "Invalid String Length" or ERR_STRING_TOO_LONG V8 (Node/Chrome) have a maximum string length that has changed over the years. Node 16 and Chrome 106 enforce a limit of `0x1fffffe8` (536870888) characters. [A 2017 V8 discussion](https://bugs.chromium.org/p/v8/issues/detail?id=6148) explains some of the background behind the V8 decision. XLSX and ODS are ZIP-based formats that store worksheets in XML entries. In worksheets with over 100M cells, the XML strings may exceed the V8 limit! Depending on the environment, this issue may result in missing worksheets; error messages such as `Invalid string length`, `ERR_STRING_TOO_LONG`, or `Cannot create a string longer than 0x1fffffe8 characters`; or browser crashes. A number of bugs have been reported to the V8 and Chromium projects on this subject, some of which have been open for nearly a decade. Please [leave a note](https://git.sheetjs.com/sheetjs/sheetjs/issues) including worksheet sizes (number of rows/columns and file size) and environment (browser or NodeJS or other platform). :::tip pass The "Excel Binary Workbook" XLSB format uses a binary representation. The XLSB parser is not affected by this issue. XLSB files are typically smaller than equivalent XLSX files. There are other Excel performance benefits to XLSB, so it is strongly recommended to use XLSB when possible. ::: #### Invalid HTML: could not find table Data can be fetched and parsed by the library: ```js const response = await fetch("test.xlsx"); const wb = XLSX.read(await response.arrayBuffer()); ``` If the file does not exist, servers will send a 404 response that may include a friendly HTML page. Without checking the response code, the integration will try to read the 404 page and fail since the HTML typically has no TABLE elements. Integration code should defend against network issues by checking status code. For example, when using `fetch`: ```js async function fetch_workbook_and_error_on_404(url) { const response = await fetch(url); if(res.status == 404) throw new Error("404 File Not Found"); const ab = await response.arrayBuffer(); return XLSX.read(ab); } ``` :::note pass When building a project with `create-react-app` or other templates, spreadsheets must be placed in the `public` folder. That folder is typically served by the dev server and copied to the production site in the build process. ::: #### Cloudflare Worker "Error: Script startup exceeded CPU time limit." This may show up in projects with many dependencies. The official workaround is dynamic `import`. For example: ```ts export default { async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise { // highlight-next-line const XLSX = await import("xlsx"); // dynamic import const wb = XLSX.read("abc\n123", {type: "string"}); const buf = XLSX.write(wb, {type: "buffer", bookType: "xlsb"}); const response = new Response(buf); response.headers.set("Content-Disposition", 'attachment; filename="cf.xlsb"'); return response; }, }; ``` #### "require is not defined" This error will be displayed in the browser console and will point to `xlsx.mjs` Older versions of Webpack do not support `mjs` for ECMAScript Modules. This typically affects older `create-react-app` projects. [The "Standalone" build](/docs/getting-started/installation/standalone) should be loaded using `require` or `import`: _CommonJS_ ```js var XLSX = require("xlsx/dist/xlsx.full.min"); ``` _ECMAScript Modules_ ```js import * as XLSX from "xlsx/dist/xlsx.full.min.js"; ``` #### SCRIPT5022: DataCloneError IE10 does not properly support `Transferable`. #### Object doesn't support property or method 'slice' IE does not implement `Uint8Array#slice`. An implementation is included in the shim script. Check [the "Standalone" Installation note](/docs/getting-started/installation/standalone#internet-explorer-and-older-browsers) #### TypeError: f.substr is not a function Some Google systems use the `base64url` encoding. `base64url` and `base64` are different encodings. A simple regular expression can translate the data: ```js var wb = XLSX.read(b64.replace(/_/g, "/").replace(/-/g, "+"), {type:'base64'}); ``` #### Error: Cannot read property '0' of undefined `FileReader#readAsText` will corrupt binary data including XLSX, XLSB, XLS, and other binary spreadsheet files. Applications should use `FileReader#readAsArrayBuffer` or `Blob#arrayBuffer`. Examples are included [in "User Submissions"](/docs/solutions/input#example-user-submissions) Applications specifically targeting legacy browsers like IE10 should use `FileReader#readAsBinaryString` to read the data and call `XLSX.read` using the `binary` type. #### `Unsupported file undefined` when reading ArrayBuffer objects Old versions of the library did not automatically detect `ArrayBuffer` objects.
Workaround (click to show) :::danger Legacy workaround This solution is not recommended for production deployments. Native support for `ArrayBuffer` was added in library version `0.9.9`. ::: After reading data with `FileReader#readAsArrayBuffer`, manually translate to binary string and call `XLSX.read` with type `"binary"` ```js document.getElementById('file-object').addEventListener("change", function(e) { var files = e.target.files,file; if (!files || files.length == 0) return; file = files[0]; var fileReader = new FileReader(); fileReader.onload = function (e) { var filename = file.name; // pre-process data var binary = ""; var bytes = new Uint8Array(e.target.result); var length = bytes.byteLength; for (var i = 0; i < length; i++) { binary += String.fromCharCode(bytes[i]); } // call 'xlsx' to read the file var oFile = XLSX.read(binary, {type: 'binary', cellDates:true, cellStyles:true}); }; fileReader.readAsArrayBuffer(file); }); ```
#### Browser is stuck! By default, operations run in the main renderer context and block the browser from updating. [Web Workers](/docs/demos/bigdata/worker) offload the hard work to separate contexts, freeing up the renderer to update. #### Strange exported file names in the web browser JS and the DOM API do not have a standard approach for creating files. There was a `saveAs` proposal as part of "File API: Writer" but it was abandoned in 2014. The library integrates a number of platform-specific techniques for different environments. In modern web browsers, the library creates an `A` element with the `download` attribute and clicks the link. A full analysis is included in the ["Local File Access" demo](/docs/demos/local/file#html5-download-attribute) If the filename looks like a UUID (hexadecimal characters and hyphens), this is a known issue with Google Tag Manager (GTM) rewriting links. There is a special [workaround](/docs/demos/local/file#google-tag-manager) for sites that use GTM. Third party libraries like `FileSaver.js` provide an implementation of `saveAs` that include more browser-specific workarounds.
FileSaver.js integration (click to show) _Standalone Build_ {`\ `} _Frameworks and Bundlers_ At the time of writing, `file-saver@2.0.5` leaks `saveAs` to the global scope, so merely importing the module works: ```js import FileSaver from 'file-saver'; // as a side effect, `saveAs` is visible import { writeFile } from 'xlsx'; // writeFile will use the global `saveAs` ```
#### "Cannot save file" in NodeJS The `fs` module is automatically loaded in scripts using `require`: ```js var XLSX = require("xlsx"); // automatically loads `fs` ``` Using the [ESM import](/docs/getting-started/installation/nodejs#esm-import), the `fs` module must be imported and passed to the library: ```js import * as XLSX from 'xlsx'; /* load 'fs' for readFile and writeFile support */ import * as fs from 'fs'; XLSX.set_fs(fs); ``` ## Data Issues #### Generated XLSX files are very large! By default, compression is disabled. Set the option `compression: true` in the `write` or `writeFile` options object. For example: ```js XLSX.writeFile(workbook, "export.xlsx", { compression: true }); ``` #### CSV and XLS files with Chinese or Japanese characters look garbled The ESM build, used in tools like Webpack and in Deno, does not include the codepage tables by default. The ["Frameworks and Bundlers"](/docs/getting-started/installation/frameworks#encoding-support) section explains how to load support. #### DBF files with Chinese or Japanese characters have underscores As mentioned in the previous answer, codepage tables must be loaded. When reading legacy files that do not include character set metadata, the `codepage` option controls the codepage. Common values: | `codepage` | Description | |-----------:|:-------------------------| | 874 | Windows Thai | | 932 | Japanese Shift-JIS | | 936 | Simplified Chinese GBK | | 950 | Traditional Chinese Big5 | | 1200 | UTF-16 Little Endian | | 1252 | Windows Latin 1 | When writing files in legacy formats like DBF, the default codepage 1252 will be used. The codepage option will override the setting. Any characters missing from the character set will be replaced with underscores. #### Worksheet only includes one row of data Some third-party writer tools will not update the dimensions records in XLSX or XLS or XLSB exports. SheetJS utility functions will skip values not in range. The following helper function will recalculate the range: ```js function update_sheet_range(ws) { var range = {s:{r:Infinity, c:Infinity},e:{r:0,c:0}}; Object.keys(ws).filter(function(x) { return x.charAt(0) != "!"; }).map(XLSX.utils.decode_cell).forEach(function(x) { range.s.c = Math.min(range.s.c, x.c); range.s.r = Math.min(range.s.r, x.r); range.e.c = Math.max(range.e.c, x.c); range.e.r = Math.max(range.e.r, x.r); }); ws['!ref'] = XLSX.utils.encode_range(range); } ```
More Code Snippets (click to show) `set_sheet_range` changes a sheet's range given a general target spec that can include only the start or end cell: ```js /* given the old range and a new range spec, produce the new range */ function change_range(old, range) { var oldrng = XLSX.utils.decode_range(old), newrng; if(typeof range == "string") { if(range.charAt(0) == ":") newrng = {e:XLSX.utils.decode_cell(range.substr(1))}; else if(range.charAt(range.length - 1) == ":") newrng = {s:XLSX.utils.decode_cell(range.substr(0, range.length - 1))}; else newrng = XLSX.utils.decode_range(range); } else newrng = range; if(newrng.s) { if(newrng.s.c != null) oldrng.s.c = newrng.s.c; if(newrng.s.r != null) oldrng.s.r = newrng.s.r; } if(newrng.e) { if(newrng.e.c != null) oldrng.e.c = newrng.e.c; if(newrng.e.r != null) oldrng.e.r = newrng.e.r; } return XLSX.utils.encode_range(oldrng); } /* call change_sheet and modify worksheet */ function set_sheet_range(sheet, range) { sheet['!ref'] = change_range(sheet['!ref'], range); } ``` _Adding a cell to a range_ ```js function range_add_cell(range, cell) { var rng = XLSX.utils.decode_range(range); var c = typeof cell == 'string' ? XLSX.utils.decode_cell(cell) : cell; if(rng.s.r > c.r) rng.s.r = c.r; if(rng.s.c > c.c) rng.s.c = c.c; if(rng.e.r < c.r) rng.e.r = c.r; if(rng.e.c < c.c) rng.e.c = c.c; return XLSX.utils.encode_range(rng); } range_add_cell("A1:C3","B2") function add_to_sheet(sheet, cell) { sheet['!ref'] = range_add_cell(sheet['!ref'], cell); } ```
#### Some decimal values are rounded Excel appears to round values in certain cases. It is suspected that the XLSX parser handles 15 decimal digits of precision. This results in inaccuracies such as `7581185.559999999` rounding to `7581185.56` and `7581185.5599999903` rounding to `7581185.55999999`. See [Issue 3003](https://git.sheetjs.com/sheetjs/sheetjs/issues/3003) in the main SheetJS CE repo for details. #### Corrupt files Third-party build tools and frameworks may post-process SheetJS scripts. The changes may result in corrupt files. In the web browser, the standalone scripts from the SheetJS CDN will use proper encodings and should work in applications. The scripts typically can be added to an `index.html` file, bypassing any third-party post-processing There are known bugs with the SWC minifier (used in Next.js 13+). The original minifier can be enabled by setting `swcMinify: false` in `next.config.js`. #### This file should be served over HTTPS `writeFile` uses platform APIs to download files. In browsers, `writeFile` uses the [`download` attribute](/docs/demos/local/file#html5-download-attribute). Newer versions of Google Chrome and other browsers will block these downloads from "insecure contexts" (when served over HTTP rather than HTTPS). Users may be presented with the option to "keep" or "save" the file: ![Download blocked](pathname:///files/dlblk.png) These limitations are enforced by the browser. It is strongly recommended to serve websites over HTTPS when possible. See [issue #3145](https://git.sheetjs.com/sheetjs/sheetjs/issues/3145) for a longer discussion.