macOS Catalina (due in late September) will be dropping support for 32bit apps. macOS Mojave has been warning us about this every time we launch one of these apps and action on your part will be needed soon. One of the most popular 32bit apps we see is Microsoft Office 2011, which includes Word, Excel and PowerPoint. If you have been limping along with Office 2008, the same warning applies. See the icons below to determine which version you have.
If you are planning on upgrading to Catalina in the fall when it is released, why not save yourself some grief and upgrade to the 2019 version of Office now? The “perpetual” version is $149 (for Word, Excel and PowerPoint) and Office 365 starts at $69 a year.