Memory increase not taken into account

Hello,

I've already tried a lot of different thoughts and a lot of research, nothing working in my case, so here it is.

I am using "vSphere client version 6.5.0.13000" and I came across an issue I don't understand.

I'm trying to increase the memory of a VM, from 8 to 16Go. The thing is, when validating, nothing happens, and the amount remains the same. Changing it on my others VMs works fine, but not this one.

Eventually, I get this error :

Unexpected token (END_OBJECT), expected FIELD_NAME: missing property '_type' that is to contain type id  (for class java.lang.Exception)

at [Source: java.io.StringReader@3c1645b0; line: 54, column: 9] (through reference chain: com.vmware.vsphere.client.vm.VmConfigSpec["originalConfig"]->com.vmware.vim.binding.vim.vm.ConfigInfo["tools"]->com.vmware.vim.binding.vim.vm.ToolsConfigInfo["lastInstallInfo"]->com.vmware.vim.binding.vim.vm.ToolsConfigInfo$ToolsLastInstallInfo["fault"])

I'm posting here hoping someone has already encoutered a similar error. Is there a workaround ?

I'll be happy to provide more information about the VM, if it seems it is related to its configuration.

Thanks in advance for every thoughts you may have,

Cheers,