Cloud migrations that go badly usually don't fail on the technical execution — they fail because the planning phase underestimated dependencies, cost implications, or the operational changes the move requires.
The first question worth answering honestly is why you're migrating. "Everyone else is doing it" isn't a strategy. Cost predictability, scalability, disaster recovery and reduced operational overhead are all valid reasons, but they lead to different architecture decisions.
A full inventory of dependencies — including the ones nobody remembers configuring — is worth the time it takes. Legacy integrations, scheduled jobs and manual processes tied to the old environment are the most common source of migration surprises.
Cost is rarely a simple win. Cloud infrastructure can be cheaper or more expensive than on-premises depending on usage patterns, and the difference often comes down to whether resources are right-sized rather than provisioned for a theoretical peak.
Migrations that go well tend to be incremental — moving workloads in a sequence that lets you validate each step, rather than a single cutover weekend betting the whole business on everything working at once.