trying to activate the Base theme in Sandbox and get the following error. Any ideas? The Bundle is SuiteCommerce Extension Management and we have v2020.2.0 installed.

{
  "type": "error.SuiteScriptError",
  "name": "34005",
  "message": "Hash.update: Missing a required argument: options.input",
  "stack": [
    "createError(N/error)"
  ],
  "cause": {
    "message": "Hash.update: Missing a required argument: options.input",
    "stack": [
      "createError(N/error)",
      "getMD5Hash(/SuiteBundles/Bundle 343577/ExtensionMechanism.Server/Services/FileApiSS2.js:338)",
      "(/SuiteBundles/Bundle 343577/ExtensionMechanism.Server/Services/FileApiSS2.js:283)",
      "E(/SuiteBundles/Bundle 343577/third_parties/underscore.js:6)",
      "copyFiles(/SuiteBundles/Bundle 343577/ExtensionMechanism.Server/Services/FileApiSS2.js:267)",
      "copyTmpFile(/SuiteBundles/Bundle 343577/ExtensionMechanism.Server/JobToProcess/ImpactChangesMapReduce.js:349)",
      "map(/SuiteBundles/Bundle 343577/ExtensionMechanism.Server/JobToProcess/ImpactChangesMapReduce.js:218)",
      "createError(N/error)"
    ],
    "name": "34005"
  },
  "id": "",
  "notifyOff": false,
  "userFacing": true
}

Does the Theme activation shows 2 entries 1 for Base and 1 for Custom?

I'm getting the same error using 20.2 dev tools on our custom theme. Same theme works fine in another account using 20.1

Used 20.1 theme tools to deploy on 20.2 bundle and worked perfectly.

4 themes are listed. Base theme and 3 of our themes, neither of our themes activate.

Can you check your manifest.json and SCA target versions are specified correctly?