+
+*** XEmacs crashes mysteriously.
+
+Check whether XEmacs was configured --use-union-type. Many compilers
+are known to treat union types incompatibly with proper functioning of
+the Lisp_Object type. (Whether this is a compiler bug or nonstandard-
+conforming code in XEmacs is a moot point.) Especially with
+--with-mule, --pdump, and/or non-null --error-checking, this is known
+to produce an unreliable build with many versions of MS VC++ and GCC,
+and similar problems are likely to occur with other compilers.
+
+Symptoms are similar to garbage collection and other "wild pointer"
+bugs, ie, stack-smashing and other hard-to-debug crashes in unrelated
+code. Try reconfiguring and building without --use-union-type.
+
+--use-union-type _is_ useful to get improved _static_ type checking of
+Lisp objects. It is theoretically possible that it might help with
+aliasing bugs under optimization and improve runtime stability, but in
+practice exactly the opposite seems to be true. If you don't work on
+XEmacs C code directly, then avoid --use-union-type entirely for now.
+
+*** XEmacs crashes mysteriously in regexp-intensive applications (eg, Gnus)
+
+The regexp implementation used in XEmacs uses alloca by default for
+efficiency. alloca provides no reliable way to check for out of
+memory (in this case, stack). Normally not a problem, except for
+systems with very small default stack allocations, and applications
+that use multi-line regular expressions (ie, explicitly including ?\n)
+in moderately large files (> 100kB or so).
+
+You may get relief by increasing the amount of stack space allocated
+to your XEmacs process (a system-dependent operation, ask your
+administrator or local experts for help), or by recompiling the regexp
+module regex.c with REGEX_MALLOC defined, relinking, and redumping.
+
+*** At startup I get a warning on stderr about missing charsets:
+
+ Warning: Missing charsets in String to FontSet conversion
+
+You need to specify appropriate charsets for your locale (usually the
+value of the LANG environment variable) in .Xresources. See
+etc/Emacs.ad for the relevant resources (mostly menubar fonts and
+fontsets). Do not edit this file, it's purely informative.
+
+If you have no satisfactory fonts for iso-8859-1, XEmacs will crash.
+
+It looks like XFree86 4.x (the usual server on Linux and *BSD) has
+some braindamage where .UTF-8 locales will always generate this
+message, because the XFree86 (font)server doesn't know that UTF-8 will
+use the ISO10646-1 font registry (or a Cmap or something).
+
+If you are not using a .UTF-8 locale and see this warning for a
+character set not listed in the default in Emacs.ad, please let
+xemacs-beta@xemacs.org know about it, so we can add fonts to the
+appropriate fontsets and stifle this warning. (Unfortunately it's
+buried in Xlib, so we can't easily get rid of it otherwise.)
+
+*** Whenever I try to retrieve a remote file, I have problems.
+
+A typical error: FTP Error: USER request failed; 500 AUTH not understood.
+Thanks to giacomo boffi <giacomo.boffi@polimi.it> on comp.emacs.xemacs:
+
+ tell your ftp client to not attempt AUTH authentication (or do not
+ use FTP servers that don't understand AUTH)
+
+and notes that you need to add an element (often "-u") to
+`efs-ftp-program-args'. Use M-x customize-variable, and verify the
+needed flag with `man ftp' or other local documentation.
+