
Some verbs do not have a future or present tense form

They are called ‘insufficient’.
There are several verbs in Russian that do not have a first person singular form in the future or present tense, due to phonetic cacophony.
The most famous verb is ‘pobedit’ – to win. You cannot say “I’ll win” as “Ya pobezhy or pobezhdy”. In the future tense, it is better to say: “Ya smogy pobedit” (“I can win”). The verb ‘ubedit’ (‘to convince’) is similar. The verb ‘pylesosit’ (‘to vacuum’) doesn’t have a first person present tense. You cannot say: “Ya pylesoshy” as “I am vacuuming”, but you can say: “Ya sobirayus pylesosit” (“I am going to vacuum”).