When sending between two clients, an error message occurs -

Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or endable -fallbackfee.

What does this mean, and how do I fix it?

Log extract below....

2018-06-01T22:48:18Z Fee Calculation: Fee:16600 Bytes:166 Needed:16600 Tgt:0 (requested 0) Reason:"PayTxFee set" Decay 0.00000: Estimation: (-1 - -1) nan% 0.0/(0.0 0 mem 0.0 out) Fail: (-1 - -1) nan% 0.0/(0.0 0 mem 0.0 out)
2018-06-01T22:48:23Z CommitTransaction:
CTransaction(hash=578d837469, ver=2, vin.size=1, vout.size=2, nLockTime=157)
    CTxIn(COutPoint(a3a8c8cd92, 0), scriptSig=160014a7419391b687baff02, nSequence=4294967293)
    CScriptWitness(3045022100887e2a97a954e5300a92ddb920256955112fe0977121b1fd9b9876b8144b246602200 f067e29f0a555a914034d13b9203390448832f43277f447c42404119e5c328001, 03a0415edb85fbdbf4b9ab3b759c3f660b8e87fe57b7dc852237a5a670ee1ba791)
    CTxOut(nValue=48.99983400, scriptPubKey=a914b4f55ca5f2a9a9a67c6dd4f8a2)
    CTxOut(nValue=1.00000000, scriptPubKey=a9147bcc4af60d02ea64d6ad3dcfc0)
2018-06-01T22:48:23Z keypool keep 1001
2018-06-01T22:48:23Z AddToWallet 578d837469ebf22fe9fff4a97ad87c11ee4453ade47c36c378c9941374d4f2e9  new
2018-06-01T22:48:23Z CommitTransaction(): Transaction cannot be broadcast immediately, no-witness-yet (code 64)
2018-06-01T22:49:51Z keypool added 1 keys (1 internal), size=2000 (1000 internal)