Symptoms
Cannot upgrade Exchange organization from Exchange 2010 to Exchange 2013/2016. While clicking the button Upgrade to Newer Exchange Version under Services > E-Mail > Exchange > Organizations the following error is displayed:
Could not find a 'Exchange2013Mailstore' server with enough capacity to add the additional services. Please contact your vendor to resolve this issue.
or
Could not find a 'Exchange2016Mailstore' server with enough capacity to add the additional services. Please contact your vendor to resolve this issue.
Cause
1. In order to perform an organization upgrade the hosts with Exchange 2010 and Exchange 2013/2016 should have similar provisioning attributes.
On attempt of upgrade OA is trying to find suitable hosts using provisioning attributes specified in the service template used for subscription. In case if provisioning attributes are not the same for Exchange 2010 and Exchange 2013/2016 hosts with Exchange 2013/2016 are excluded, therefore required services for Exchange 2013/2016 will not be found and the error above will be thrown.
2. In order to perform an organization upgrade the hosts with MailStores for Exchange 2016 should have enough capacity to store Organization.
3. Limit for a Public Folder resource should be set to 0 in case Public Folders are not used by a subscription and resource usage is 0.
Resolution
1. Ensure that Exchange 2010 and Exchange 2013/2016 service nodes have the same provisioning attribute and repeat the upgrade procedure.
2. Ensure that MailStores for Exchange 2013/2016 have enough capacity.
3. Make sure that Public Folder resource limit is set to 0.