# Frequently asked questions
## There seems to be a problem with character encoding...
It is necessary to use UTF-8 encoding for all texts in PhpSpreadsheet. If the script uses different encoding then you can convert those texts with PHP's `iconv()` or `mb_convert_encoding()` functions.
## Fatal error: Allowed memory size of xxx bytes exhausted (tried to allocate yyy bytes) in zzz on line aaa
PhpSpreadsheet holds an "in memory" representation of a spreadsheet, so it is susceptible to PHP's memory limitations. The memory made available to PHP can be increased by editing the value of the `memory_limit` directive in your `php.ini` file, or by using `ini_set('memory_limit', '128M')` within your code.
Some Readers and Writers are faster than others, and they also use differing amounts of memory.
## Protection on my worksheet is not working?
When you make use of any of the worksheet protection features (e.g. cell range protection, prohibiting deleting rows, ...), make sure you enable worksheet security. This can for example be done like this:
``` php $spreadsheet->getActiveSheet()->getProtection()->setSheet(true); ```
## Feature X is not working with Reader\_Y / Writer\_Z
Not all features of PhpSpreadsheet are implemented in all of the Reader / Writer classes. This is mostly due to underlying libraries not supporting a specific feature or not having implemented a specific feature.
For example autofilter is not implemented in PEAR Spreadsheet\_Excel\_writer, which is the base of our Xls writer.
We are slowly building up a list of features, together with the different readers and writers that support them, in the [features cross reference](./references/features-cross-reference.md).
## Formulas don't seem to be calculated in Excel2003 using compatibility pack?
This is normal behaviour of the compatibility pack, `Xlsx` displays this correctly. Use `\PhpOffice\PhpSpreadsheet\Writer\Xls` if you really need calculated values, or force recalculation in Excel2003.
## Setting column width is not 100% accurate
Trying to set column width, I experience one problem. When I open the file in Excel, the actual width is 0.71 less than it should be.
The short answer is that PhpSpreadsheet uses a measure where padding is included. See [how to set a column's width](./topics/recipes.md#setting-a-columns-width) for more details.