MissingPackageManifestError

I recently started getting a Missing Package Manifest error when trying to build a project I have been building for more than a year.
I have tried removing both the .pio and .platformio folder before running, and removed most library dependencies from platformio.ini in order to locate the error.
Is there any way of locating where the missing manifest should be?

Output from attempting to build after deleting .platfromio and .pio (some urls removed due to limitations for new users):
Processing firmware (platform: ststm32; framework: mbed; board: GENERIC_STM32L433CCY)

Platform Manager: Installing ststm32
Downloading [####################################] 100%
Unpacking [####################################] 100%
Platform Manager: ststm32@17.6.0 has been installed!
Tool Manager: Installing platformio/toolchain-gccarmnoneeabi @ 1.120301.0
Tool Manager: Warning! Package Mirror: Got the unrecognized status code ‘403’ when downloaded toolchain-gccarmnoneeabi-linux_x86_64-1.120301.0.tar.gz
Tool Manager: Looking for another mirror…
Downloading [####################################] 100%
Unpacking [####################################] 100%
Tool Manager: toolchain-gccarmnoneeabi@1.120301.0 has been installed!
Tool Manager: Installing platformio/framework-mbed @ ~6.61700.0
Tool Manager: Warning! Package Mirror: Got the unrecognized status code ‘403’ when downloaded framework-mbed-6.61700.231105.tar.gz
Tool Manager: Looking for another mirror…
Downloading [####################################] 100%
Unpacking [####################################] 100%
Tool Manager: framework-mbed@6.61700.231105 has been installed!
Tool Manager: Installing platformio/tool-scons @ ~4.40801.0
Tool Manager: Warning! Package Mirror: Got the unrecognized status code ‘403’ when downloaded tool-scons-4.40801.0.tar.gz
Tool Manager: Looking for another mirror…
Downloading [####################################] 100%
Unpacking [####################################] 100%
Tool Manager: tool-scons@4.40801.0 has been installed!
MissingPackageManifestError: Could not find one of ‘library.json, library.properties, module.json’ manifest files in the package

I solved this issue by moving the mbed folder to the root of the project. Dont know why this worked.