There is insufficient system memory in resource pool 'default' to run this query

So while running a really generic restore to the SQL Server cluster instance sql1:

USE [master] RESTORE DATABASE [enron]  FROM  DISK = N'\\ServerE\iso\enron.bak' WITH  FILE = 1,  MOVE N'enron_Data' TO N'C:\Data\enron_Data.mdf',  MOVE N'enron_Log' TO N'C:\Data\enron_Log.ldf',  NOUNLOAD,  REPLACE,  STATS = 5 GO

The error, while descriptive, was interesting because it was "terse" :)

Msg 3224, Level 16, State 2, Line 2 Error: 3224, Severity: 16, State: 2. (Params:). The error is printed in terse mode because there was error during formatting. Tracing, ETW, notifications etc are skipped. Msg 3013, Level 16, State 1, Line 2 RESTORE DATABASE is terminating abnormally. Msg 701, Level 17, State 123, Line 2 There is insufficient system memory in resource pool 'default' to run this query. Completion time: 2021-02-04T03:18:26.1654581-08:00

Turns out, the RAM for the server was still set at it's installation default of 128 MB.

Once that was increased to 1024 MB, the problem magically went away.