Why gets 'The size of the file should be smaller than 120M' when upgrading P-series firmware

[Issue Description]

When upgrading the P-series PBX firmware gets the error 'The size of the file should be smaller than 120M' 

[Applicable Models]

P-series PBX

[Solution]

Please upgrade the PBX to the below firmware first, then upgrade to the latest firmware
http://download.yeastar.com/YeastarSupport/image/37.4.0.18.bin
 
PS: Since the current PBX firmware is very old, please enable reset to factory default when upgrading.