In 811 after a relatively successful yet inconclusive raiding caimpaign by the Byzantines against the growing state of the Bulgars, the emperor Nicephorus was ambushed while passing through a mountain pass he didn't scout and he and his army were decisively defeated and Nicephorus was killed in the battle while his son gravely injured. After this Michael I would take power and attempt at resolve the situation, but he was soon removed from power and Leo the Armenian and years later the Armorican dynasty took power, which would initiate the second iconoclastic period that would last for 3 decades.
So the question is, what would happen if this battle is completely avoided? This means Nicephorus managed to get back to Byzantium safely, there a couple of possible things that could be avoided:
-Thomas the Slav's rebellion.
-No more Iconoclasm
-No Bulgarian ascendancy
-No takeover of Sicily by the Aglabids
-No takeover of Crete by the Andalusian corsairs
-Different diplomatic relations between the Byzantine and Charlemagne.
Is it possible for a continuing rule by Nicephorus to be far more stable than what IOTL happened? If yes, can the Arabs be repulsed in their attempts at conquering Sicily and Crete during this time period?