Sometimes it is necessary to change extension names on the server to reflect major library updates. The names and the extensions on the local machine then become invalid and it could happen that after an update you're missing extensions and some programs do not start any longer. If that happens, please follow this procedure first:
1. Run Apps tool
2. Click on Apps => Maintenance => Dependencies and Deletions
3. Click on Dependencies => Update .dep Files
4. Click on Fetch Missing Dependencies
This should solve such issues. In the current release cycle, there were some changes in ffmpeg, libvpx, gnutls, which could cause the problems mentioned above. If you're installing from scratch, there will be no problems, just when you had the renamed extensions locally (e.g. gnutls.tcz became gnutls2.tcz and a new gnutls.tcz was introduced, which is of version 3).