This is one of the most-referenced entries I've made in my department's shared notes, so it seemed like a good choice for my first post to a wider audience!

Signature required

• Does your task server require scripts to be signed?
  • If so, do you have a valid code signing certificate and is your script signed?
• If your script is signed, is the signature still valid? Here's how to check: Get-AuthenticodeSignature -FilePath your-script.ps1
  • If it's not valid, sign it again (I have a shortcut to do this in my PowerShell profile)

Who's running things?

• Is the task set to run whether or not the user is logged on?
• Do you have a specific account that runs scheduled tasks?
  • Did you save the correct password when setting up the task?
  • Just try the password one more time... I won't tell anyone you tried typing it instead of copying and pasting 😅
• Does the user/script-running account have the correct permissions to do everything you need it to?
  • Folder permissions are a common issue

Trust issues

• Does the account running the script trust your signature?
  • You may need to trust/re-trust your signature, especially if you were recently issued a new code signing cert
• If possible, on the machine running the task, open up a command prompt (or PowerShell!) and try launching PowerShell as the user running the task: runas /user:example.edu\taskrunner powershell.exe
  • Try running your script in the new PowerShell window that just popped up
  • When it asks you to trust your script, you say yes [A]lways!

I hope this saves at least a few people from a few moments of frustration. There are weirder issues out there for sure, but this checklist should help you solve the most common ones!