Blocker in client project : either DIY, or look for workarounds, or escalate to client and reduce scope. Planning gets suitably modified for rest of the week and month.

Blocker in personal projects : some of my ideas have turned out to be not as easily implementable as I had first imagined. I usually reduce scope - because the idea after all started off as part of some life goal - but I have also dropped some ideas entirely. I record the reasons in the project directory to revisit later. I deliberately avoid overanalyzing in such cases - as somebody prone to procrastination, overanalysis of a tough idea is like entering a blackhole for me.