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Garbled text as a result of incorrect character encodings

Mojibake (文字化け; , "character transformation") is the garbled or gibberish text that is the result of text being decoded using an unintended character encoding. The result is a systematic replacement of symbols with completely unrelated ones, often from a different writing system. This display may include the generic replacement character ("�") in places where the binary representation is considered invalid. A replacement can also involve multiple consecutive symbols, as viewed in one encoding, when the same binary code constitutes one symbol in the other encoding. This is either because of differing constant length encoding (as in Asian 16 bit encodings vs European 8 bit encodings), or the use of variable length encodings (notably UTF 8 and UTF 16). Failed rendering of glyphs due to either missing fonts or missing glyphs in a font is a different issue that is not to be confused with mojibake. Symptoms of this failed rendering include blocks with the code point displayed in hexadecimal or using the generic replacement character. Importantly, these replacements are valid and are the result of correct error handling by the software.

If the encoding is not specified, it is up to the software to decide it by other means. Depending on the type of software, the typical solution is either configuration or charset detection heuristics. Both are prone to mis prediction. The encoding of text files is affected by locale setting, which depends on the user's language, brand of operating system, and many other conditions. Therefore, the assumed encoding is systematically wrong for files that come from a computer with a different setting, or even from a differently localized software within the same system. For Unicode, one solution is to use a byte order mark, but for source code and other machine readable text, many parsers do not tolerate this. Another is storing the encoding as metadata in the file system. File systems that support extended file attributes can store this as user. charset. This also requires support in software that wants to take advantage of it, but does not disturb other software. While a few encodings are easy to detect, such as UTF 8, there are many that are hard to distinguish (see charset detection). A web browser may not be able to distinguish a page coded in EUC JP and another in Shift JIS if the encoding is not assigned explicitly using HTTP headers sent along with the documents, or using the HTML document's meta tags that are used to substitute for missing HTTP headers if the server cannot be configured to send the proper HTTP headers; see character encodings in HTML.

Mojibake also occurs when the encoding is incorrectly specified. This often happens between encodings that are similar. For example, the Eudora email client for Windows was known to send emails labelled as ISO 8859 1 that were in reality Windows 1252. Windows 1252 contains extra printable characters in the C1 range (the most frequently seen being curved quotation marks and extra dashes), that were not displayed properly in software complying with the ISO standard; this especially affected software running under other operating systems such as Unix.

Of the encodings still in common use, many originated from taking ASCII and appending atop it; as a result, these encodings are partially compatible with each other. Examples of this include Windows 1252 and ISO 8859 1. People thus may mistake the expanded encoding set they are using with plain ASCII.

When there are layers of protocols, each trying to specify the encoding based on different information, the least certain information may be misleading to the recipient. For example, consider a web server serving a static HTML file over HTTP. The character set may be communicated to the client in any number of 3 ways:
in the HTTP header. This information can be based on server configuration (for instance, when serving a file off disk) or controlled by the application running on the server (for dynamic websites). in the file, as an HTML meta tag (http equiv or charset) or the encoding attribute of an XML declaration. This is the encoding that the author meant to save the particular file in. in the file, as a byte order mark. This is the encoding that the author's editor actually saved it in. Unless an accidental encoding conversion has happened (by opening it in one encoding and saving it in another), this will be correct. It is, however, only available in Unicode encodings such as UTF 8 or UTF 16.

Much older hardware is typically designed to support only one character set and the character set typically cannot be altered. The character table contained within the display firmware will be localized to have characters for the country the device is to be sold in, and typically the table differs from country to country. As such, these systems will potentially display mojibake when loading text generated on a system from a different country. Likewise, many early operating systems do not support multiple encoding formats and thus will end up displaying mojibake if made to display non standard text—early versions of Microsoft Windows and Palm OS for example, are localized on a per country basis and will only support encoding standards relevant to the country the localized version will be sold in, and will display mojibake if a file containing a text in a different encoding format from the version that the OS is designed to support is opened.

Applications using UTF 8 as a default encoding may achieve a greater degree of interoperability because of its widespread use and backward compatibility with US ASCII. UTF 8 also has the ability to be directly recognised by a simple algorithm, so that well written software should be able to avoid mixing UTF 8 up with other encodings. The difficulty of resolving an instance of mojibake varies depending on the application within which it occurs and the causes of it. Two of the most common applications in which mojibake may occur are web browsers and word processors. Modern browsers and word processors often support a wide array of character encodings. Browsers often allow a user to change their rendering engine's encoding setting on the fly, while word processors allow the user to select the appropriate encoding when opening a file. It may take some trial and error for users to find the correct encoding. The problem gets more complicated when it occurs in an application that normally does not support a wide range of character encoding, such as in a non Unicode computer game. In this case, the user must change the operating system's encoding settings to match that of the game. However, changing the system wide encoding settings can also cause Mojibake in pre existing applications. In Windows XP or later, a user also has the option to use Microsoft AppLocale, an application that allows the changing of per application locale settings. Even so, changing the operating system encoding settings is not possible on earlier operating systems such as Windows 98; to resolve this issue on earlier operating systems, a user would have to use third party font rendering applications.

Mojibake in English texts generally occurs in punctuation, such as em dashes (—), en dashes (–), and curly quotes (“,”,‘,’), but rarely in character text, since most encodings agree with ASCII on the encoding of the English alphabet. For example, the pound sign £ will appear as £ if it was encoded by the sender as UTF 8 but interpreted by the recipient as one of the Western European encodings (CP1252 or ISO 8859 1). If iterated using CP1252, this can lead to £, £, £, ÃƒÆ’Ã¢â‚¬à ¡Ãƒâ€šÃ‚Â£, and so on. Similarly, the right single quotation mark (’), when encoded in UTF 8 and decoded using Windows 1252, becomes ’, ’, ’, and so on. Some computers did, in older eras, have vendor specific encodings which caused mismatch also for English text. Commodore brand 8 bit computers used PETSCII encoding, particularly notable for inverting the upper and lower case compared to standard ASCII. PETSCII printers worked fine on other computers of the era, but inverted the case of all letters. IBM mainframes use the EBCDIC encoding which does not match ASCII at all.

Users of Central and Eastern European languages can also be affected. Because most computers were not connected to any network during the mid to late 1980s, there were different character encodings for every language with diacritical characters (see ISO/IEC 8859 and KOI 8), often also varying by operating system.

In Hungarian, the phenomenon is referred to as betűszemét, meaning "letter garbage". Hungarian has been particularly susceptible as it contains the accented letters á, é, í, ó, ú, ö, ü (all present in the Latin 1 character set), plus the two characters ő and ű which are not in Latin 1. These two characters can be correctly encoded in Latin 2, Windows 1250, and Unicode. However, before Unicode became common in e mail clients, e mails containing Hungarian text often had the letters ő and ű corrupted, sometimes to the point of unrecognizability. It is common to respond to a corrupted e mail with the nonsense phrase "Árvíztűrő tükörfúrógép" (literally "Flood resistant mirror drilling machine") which contains all accented characters used in Hungarian.

Hungarian example Source encoding Target encoding Result Occurrence ÁRVÍZTŰRŐ TÜKÖRFÚRÓGÉPárvíztűrő tükörfúrógép UTF 8 Quoted printable 7 bit ASCII =C3=81RV=C3=8DZT=C5=B0R=C5=90 T=C3=9CK=C3=96RF=C3=9AR=C3=93G=C3=89P =C3=A1rv=C3=ADzt=C5=B1r=C5=91 t=C3=BCk=C3=B6rf=C3=BAr=C3=B3g=C3=A9p Mainly caused by incorrectly configured mail servers but may occur in SMS messages on some cell phones as well. ISO 8859 2 Quoted printable =C1RV=CDZT=DBR=D5 T=DCK=D6RF=DAR=D3G=C9P=E1rv=EDzt=FBr=F5 t=FCk=F6rf=FAr=F3g=E9p CWI 2 CP 437 ÅRVìZTÿRº TÜKÖRFùRòGÉPárvíztûrô tükörfúrógép The CWI 2 encoding was designed so that Hungarian text remains fairly well readable even if the device on the receiving end uses one of the default encodings (CP 437 or CP 850). This encoding was used very heavily between the early 1980s and early 1990s, but nowadays it is completely deprecated. CP 852 ╡RV╓ZTδRè TÜKÖRFΘRαGÉPárvízt√rï tükörfúrógép This was very common in the days of DOS, as the text was often encoded using code page 852 ("Central European"), but the software on the receiving end often did not support CP 852 and instead tried to display text using CP 437 or CP 850. Lowercase letters are mainly correct, except for ű and ő. Ü/ü and Ö/ö are correct because CP 437 and CP 850 were made compatible with German. Although this is rare nowadays, it can still be seen in places such as on printed prescriptions and cheques. CP 850 ÁRVÍZTÙRè TÜKÖRFÚRÓGÉPárvízt¹rï tükörfúrógép Windows 1250 µRVÖZTëRŠ TšK™RFéRŕGP rvˇztűr‹ tk"rfŁr˘g‚p Both encodings are Central European, but the text is encoded with the DOS encoding and decoded with the Windows encoding. The use of ű is correct. Mac Roman µRV÷ZTÎRä TöKôRFÈR‡GêP†rv°zt˚rã tÅkîrf£r¢gÇp Also common in the days of DOS, this could be seen when Apple computers tried to display Hungarian text sent using DOS or Windows machines, as they would often default to Apple's own encoding. Windows 1250 ¡RVÕZT€R’ T‹K÷RF⁄R”G P·rvÌzt˚rı t¸kˆrf˙rÛgÈp CP 852 ┴RV═ZT█RŇ T▄KÍRF┌RËG╔PßrvÝztűr§ tŘk÷rf˙rˇgÚp Both encodings are Central European, but the text is encoded with the Windows encoding and decoded with the DOS encoding. The use of ű is correct. Windows 1252 ÁRVÍZTÛRÕ TÜKÖRFÚRÓGÉPárvíztûrõ tükörfúrógép The default Western European Windows encoding is used instead of the Central European one. Only ő Ő (õ Õ) and ű Ű (û Û) are wrong, and the text is completely readable. This is the most common error nowadays; due to ignorance, it occurs often on webpages or even in printed media. UTF 8 ÁRVÍZTÅ°RŐ TÃœKÖRFÚRÃ"GÉPárvÃztűrÅ‘ tükörfúrógép Mainly caused by web services or webmail clients that are configured incorrectly or not tested for international usage (as the problem remains concealed for English texts). In this case the actual (often generated) content is in UTF 8, but some older software may default to localized encodings if UTF 8 is not explicitly specified in the HTML headers. Mac Roman √ÅRV√çZT≈∞R≈ê T√úK√ñRF√öR√ìG√âP√°rv√≠zt≈±r≈ë t√ºk√∂rf√∫r√≥g√©p

Prior to the creation of ISO 8859 2 in 1987, users of various computing platforms used their own character encodings such as AmigaPL on Amiga, Atari Club on Atari ST and Masovia, IBM CP852, Mazovia and Windows CP1250 on IBM PCs. Polish companies selling early DOS computers created their own mutually incompatible ways to encode Polish characters and simply reprogrammed the EPROMs of the video cards (typically CGA, EGA, or Hercules) to provide hardware code pages with the needed glyphs for Polish—arbitrarily located without reference to where other computer sellers had placed them. The situation began to improve when, after pressure from academic and user groups, ISO 8859 2 succeeded as the "Internet standard" with limited support of the dominant vendors' software (today largely replaced by Unicode). With the numerous problems caused by the variety of encodings, even today some users tend to refer to Polish diacritical characters as krzaczki (, lit. "little shrubs").

Croatian, Bosnian, Serbian (the seceding varieties of Serbo Croatian language) and Slovenian add to the basic Latin alphabet the letters š, đ, č, ć, ž, and their capital counterparts Š, Đ, Č, Ć, Ž (only č/Č, š/Š and ž/Ž in Slovenian; officially, although others are used when needed, mostly in foreign names, as well). All of these letters are defined in Latin 2 and Windows 1250, while only some (š, Š, ž, Ž, Đ) exist in the usual OS default Windows 1252, and are there because of some other languages. Although Mojibake can occur with any of these characters, the letters that are not included in Windows 1252 are much more prone to errors. Thus, even nowadays, "šđčćž ŠĐČĆŽ" is often displayed as "šðèæž ŠÐÈÆŽ", although ð, È, and Æ are never used in Slavic languages. When confined to basic ASCII (most user names, for example), common replacements are: š→s, đ→dj, č→c, ć→c, ž→z (capital forms analogously, with Đ→Dj or Đ→DJ depending on word case). All of these replacements introduce ambiguities, so reconstructing the original from such a form is usually done manually if required. The Windows 1252 encoding is important because the English versions of the Windows operating system are most widespread, not localized ones. The reasons for this include a relatively small and fragmented market, increasing the price of high quality localization, a high degree of software piracy (in turn caused by high price of software compared to income), which discourages localization efforts, and people preferring English versions of Windows and other software. The drive to differentiate Croatian from Serbian, Bosnian from Croatian and Serbian, and now even Montenegrin from the other three creates many problems. There are many different localizations, using different standards and of different quality. There are no common translations for the vast amount of computer terminology originating in English. In the end, people use English loanwords ("kompjuter" for "computer", "kompajlirati" for "compile," etc. ), and if they are unaccustomed to the translated terms, they may not understand what some option in a menu is supposed to do based on the translated phrase. Therefore, people who understand English, as well as those who are accustomed to English terminology (who are most, because English terminology is also mostly taught in schools because of these problems) regularly choose the original English versions of non specialist software. When Cyrillic script is used (for Macedonian and partially Serbian), the problem is similar to other Cyrillic based scripts. Newer versions of English Windows allow the code page to be changed (older versions require special English versions with this support), but this setting can be and often was incorrectly set. For example, Windows 98 and Windows Me can be set to most non right to left single byte code pages including 1250, but only at install time.

The writing systems of certain languages of the Caucasus region, including the scripts of Georgian and Armenian, may produce mojibake. This problem is particularly acute in the case of ArmSCII or ARMSCII, a set of obsolete character encodings for the Armenian alphabet which have been superseded by Unicode standards. ArmSCII is not widely used because of a lack of support in the computer industry. For example, Microsoft Windows does not support it.

Another type of mojibake occurs when text encoded in a single byte encoding is erroneously parsed in a multi byte encoding, such as one of the encodings for East Asian languages. With this kind of mojibake more than one (typically two) characters are corrupted at once. For example, if the Swedish word kärlek is encoded in Windows 1252 but decoded using GBK, it will appear as "k鋜lek", where "är" is parsed as "鋜". Compared to the above mojibake, this is harder to read, since letters unrelated to the problematic å, ä or ö are missing, and is especially problematic for short words starting with å, ä or ö (e. g. "än" becomes "鋘"). Since two letters are combined, the mojibake also seems more random (over 50 variants compared to the normal three, not counting the rarer capitals). In some rare cases, an entire text string which happens to include a pattern of particular word lengths, such as the sentence "Bush hid the facts", may be misinterpreted.

A similar effect can occur in Brahmic or Indic scripts of South Asia, used in such Indo Aryan or Indic languages as Hindustani (Hindi Urdu), Bengali, Punjabi, Marathi, and others, even if the character set employed is properly recognized by the application. This is because, in many Indic scripts, the rules by which individual letter symbols combine to create symbols for syllables may not be properly understood by a computer missing the appropriate software, even if the glyphs for the individual letter forms are available. One example of this is the old Wikipedia logo, which attempts to show the character analogous to "wi" (the first syllable of "Wikipedia") on each of many puzzle pieces. The puzzle piece meant to bear the Devanagari character for "wi" instead used to display the "wa" character followed by an unpaired "i" modifier vowel, easily recognizable as mojibake generated by a computer not configured to display Indic text. The logo as redesigned as of 2010 has fixed these errors. The idea of Plain Text requires the operating system to provide a font to display Unicode codes. This font is different from OS to OS for Singhala and it makes orthographically incorrect glyphs for some letters (syllables) across all operating systems. For instance, the 'reph', the short form for 'r' is a diacritic that normally goes on top of a plain letter. However, it is wrong to go on top of some letters like 'ya' or 'la' in specific contexts. For Sanskritic words or names inherited by modern languages, such as कार्य, IAST: kārya, or आर्या, IAST: āryā, it is apt to put it on top of these letters. By contrast, for similar sounds in modern languages which result from their specific rules, it is not put on top, such as the word करणाऱ्या, IAST: karaṇāryā, a stem form of the common word करणारा/री, IAST: karaṇārā/rī, in the Marathi language. But it happens in most operating systems. This appears to be a fault of internal programming of the fonts. In Mac OS and iOS, the muurdhaja l (dark l) and 'u' combination and its long form both yield wrong shapes. Some Indic and Indic derived scripts, most notably Lao, were not officially supported by Windows XP until the release of Vista. However, various sites have made free to download fonts.

Due to Western sanctions and the late arrival of Burmese language support in computers, In the Zawgyi font, some codepoints for Burmese script were implemented as specified in Unicode, but others were not. The Unicode Consortium refers to this as ad hoc font encodings. With the advent of mobile phones, mobile vendors such as Samsung and Huawei simply replaced the Unicode compliant system fonts with Zawgyi versions. Myanmar government designated 1 October 2019 as "U Day" to officially switch to Unicode.

In certain writing systems of Africa, unencoded text is unreadable. Texts that may produce mojibake include those from the Horn of Africa such as the Ge'ez script in Ethiopia and Eritrea, used for Amharic, Tigre, and other languages, and the Somali language, which employs the Osmanya alphabet. In Southern Africa, the Mwangwego alphabet is used to write languages of Malawi and the Mandombe alphabet was created for the Democratic Republic of the Congo, but these are not generally supported. Various other writing systems native to West Africa present similar problems, such as the N'Ko alphabet, used for Manding languages in Guinea, and the Vai syllabary, used in Liberia.

Another affected language is Arabic (see below), in which text becomes completely unreadable when the encodings do not match.