Error: [UPLOAD_FAIL] Some error occurred in uploading the plugin. Please contact your administrator

I know I'm late to the game but this exact issue happened with us today and I wanted to share how we ended up resolving it.  This is what I did:

First I created a brand new project in another directory with li create-project.  (My broken project was in ~/khoros/sdk so I created the directory ~/khoros/new_sdk and created the project in there with the name sdk to match the original, which means I ended up with the directory ~/khoros/new_sdk/sdk as my root project path.)

Whenever I create a new SDK project I always get the "Cannot find module 'object.defaults'" error described in this post and need to perform the workaround from Denizbaby provided here and shown below.

# rm -rf ~/khoros/new_sdk/sdk/node_modules
# cd ~/khoros/new_sdk/sdk && npm install​

I then entered the new root project directory and used the li export-plugin --force and li submit-plugin --force --dryrun commands to verify that the new project was working as expected.

I didn't want to sever the symbolic links that were present and being used by some automated scripts, so rather than just moving/renaming the bad sdk directory and moving the working new_sdk/sdk directory into its place,  I created a copy of the broken SDK project, deleted everything inside the broken sdk/ directory, and then copied everything from the working new_sdk/sdk/ directory into the original location. 

This is illustrated in the code snippet and screenshot below.

# mkdir ~/khoros/sdk.bad.2021-01-15
# cp -r ~/khoros/sdk/* ~/khoros/sdk.bad.2021-01-15/
# rm -rf ~/khoros/sdk/*
# cp -ar ~/khoros/new_sdk/sdk/* sdk/​

I then tried running li submit-plugin --force (with and without --dryrun) in the original directory (sdk/) with the new files present, and it was successful.

I hope this helps anyone who runs into this issue in the future, because it was a beast to troubleshoot.  🙂