UK TeX FAQ -- question label altabcr

### Alignment tab changed to `\``cr`

This is an error you may encounter in LaTeX when a tabular environment is being processed. “Alignment tabs” are the `&` signs that separate the columns of a `tabular` (or `array` or matrix) environment; so the error message

>     ! Extra alignment tab has been changed to \cr

could arise from a simple typo, such as:

>     \begin{tabular}{ll}
>       hello   & there & jim \\
>       goodbye & now
>     \end{tabular}

where the second `&` in the first line of the table is more than the two-column `ll` column specification can cope with. In this case, an extra “`l`” in that solves the problem. (If you continue from the error in this case, “`jim`” will be moved to a row of his own.) Another simple typo that can provoke the error is:

>     \begin{tabular}{ll}
>       hello   & there
>       goodbye & now
>     \end{tabular}

where the ‘`\\`’ has been missed from the first line of the table. In this case, if you continue from the error, you will find that LaTeX has made a table equivalent to:

>     \begin{tabular}{ll}
>       hello   & there goodbye\\
>       now
>     \end{tabular}

(with the second line of the table having only one cell).

Rather more difficult to spot is the occurrence of the error when you’re using alignment instructions in a “`p`” column:

>     \usepackage{array}
>     ...
>     \begin{tabular}{l>{\raggedright}p{2in}}
>     here & we are again \\
>     happy & as can be
>     \end{tabular}

the problem here (as explained in tabular cell alignment) is that the `\``raggedright` command in the column specification has overwritten `tabular`’s definition of `\\`, so that “`happy`” appears in a new line of the second column, and the following `&` appears to LaTeX just like the second `&` in the first example above.

Get rid of the error in the way described in tabular cell alignment — either use `\``tabularnewline` explicitly, or use the `\``RBS` trick described there.

The amsmath package adds a further twist; when typesetting a matrix (the package provides many matrix environments), it has a fixed maximum number of columns in a matrix — exceed that maximum, and the error will appear. By default, the maximum is set to 10, but the value is stored in counter `MaxMatrixCols` and may be changed (in the same way as any counter):

>     \setcounter{MaxMatrixCols}{20}

`array.sty`
  Distributed as part of macros/latex/required/tools (or browse the directory); catalogue entry

This answer last edited: 2011-07-06

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