I have a problem with
amsmath package. After an update this package was removed because it was obsolete. But what package can use instead of
MiKTeX has reorganized the package
amslatex. Therefore the update removes it:
amslatex is split in
amscls. (Also there is a new package
However, the update has not installed the new packages automatically. Therefore I have installed them manually. For AmSLaTeX you need at least
amsmath. It contains the package file
amscls contains the AMS classes (
Finally the local repository database is synchronized by calling the MiKTeX Package Manager, menu item
Synchronize, see comment of Ulrike Fischer.
amsmath is definitely not obsolete! It may have some old and unrepaired bugs, but it still has the status "maintained" and AMS has every intention of keeping it that way.
Something else must have gone wrong with your update.
amsmath and the AMS document classes +
amsthm used to be combined on CTAN under the name
amslatex. They have always been separate in TeX Live, and, although originally bundled together on the AMS server, were repackaged in mid-2010 to be distributed in two parts.
This split was implemented in late January on CTAN, concurrent with a minor update (version 2.14) "to provide more fluid interoperability with stix.sty. It should be fully compatible with version 2.13."
The consequences of this change (and the ensuing confusion) eluded me when i first answered this question, a fact for which i apologize.
You can use
mathtools instead (you should it instead of
amsmath because it fixes a bug).
I had a similar problem today. I ran the update a second time, and that eliminated the error message.
After manually installing package
amslatex-primer, you might have an error about
etex.sty not found.
You can fix it by using "Package Manager (Admin)" from MiKTeX 2.9.
Choose Repository > Synchronize