I was importing a CRM Managed Solution and the import failed with the following error:
"The assembly content size '8399872 bytes' has exceeded the maximum value allowed for isolated plug-ins '8388608 bytes'."
I know you can argue that even for a dll can be to much and it was something Microsoft was trying to avoid, however sometimes can really happen. To overcome this issue, a key on the [DeploymentProperties] table can be updated to a bigger value.
With me the problem was the utilization of an external dll that i used for some testing, totally forgot to remove the reference.
But, if in anytime someone has to use a dll that has more than 8.192 of size, the default of CRM, the following sql query can override that value for a bigger value.
SET [IntColumn] = 16384
WHERE [ColumnName] = 'SandboxClientMaxAssemblySizeInKByte'
Hope it helps.