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A security policy change, a newer version of MacOS or Windows OS, or a switch in CPU architecture to ARM could stop the applications from working. But it is time to tell your clients that this won't work forever.
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You can of course continue for a few years with FileMaker Pro 18 Advanced to create and deploy runtimes. If you still depend on building runtimes, it's time to consider moving yourself and your customers in a new direction. deprecated the FileMaker runtime feature in version 14 and recently announced its removal for the upcoming version 19 in May 2020.
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